session
Manage browser sessions, cookies, cache, proxy settings, etc.
Process: Main
The session module can be used to create new Session objects.
You can also access the session of existing pages by using the session
property of WebContents, or from the session module.
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('https://github.com')
const ses = win.webContents.session
console.log(ses.getUserAgent())
Methods
The session module has the following methods:
session.fromPartition(partition[, options])
partitionstring
Returns Session - A session instance from partition string. When there is an existing
Session with the same partition, it will be returned; otherwise a new
Session instance will be created with options.
If partition starts with persist:, the page will use a persistent session
available to all pages in the app with the same partition. if there is no
persist: prefix, the page will use an in-memory session. If the partition is
empty then default session of the app will be returned.
To create a Session with options, you have to ensure the Session with the
partition has never been used before. There is no way to change the options
of an existing Session object.
session.fromPath(path[, options])
pathstring
Returns Session - A session instance from the absolute path as specified by the path
string. When there is an existing Session with the same absolute path, it
will be returned; otherwise a new Session instance will be created with options. The
call will throw an error if the path is not an absolute path. Additionally, an error will
be thrown if an empty string is provided.
To create a Session with options, you have to ensure the Session with the
path has never been used before. There is no way to change the options
of an existing Session object.
Properties
The session module has the following properties:
session.defaultSession
A Session object, the default session object of the app.
Class: Session
Get and set properties of a session.
Process: Main
This class is not exported from the 'electron' module. It is only available as a return value of other methods in the Electron API.
You can create a Session object in the session module:
const { session } = require('electron')
const ses = session.fromPartition('persist:name')
console.log(ses.getUserAgent())
Instance Events
The following events are available on instances of Session:
Event: 'will-download'
Returns:
eventEventitemDownloadItemwebContentsWebContents
Emitted when Electron is about to download item in webContents.
Calling event.preventDefault() will cancel the download and item will not be
available from next tick of the process.
const { session } = require('electron')
session.defaultSession.on('will-download', (event, item, webContents) => {
event.preventDefault()
require('got')(item.getURL()).then((response) => {
require('node:fs').writeFileSync('/somewhere', response.body)
})
})
Event: 'extension-loaded'
Returns:
eventEventextensionExtension
Emitted after an extension is loaded. This occurs whenever an extension is added to the "enabled" set of extensions. This includes:
- Extensions being loaded from
Session.loadExtension. - Extensions being reloaded:
- from a crash.
- if the extension requested it (
chrome.runtime.reload()).
Event: 'extension-unloaded'
Returns:
eventEventextensionExtension
Emitted after an extension is unloaded. This occurs when
Session.removeExtension is called.
Event: 'extension-ready'
Returns:
eventEventextensionExtension
Emitted after an extension is loaded and all necessary browser state is initialized to support the start of the extension's background page.
Event: 'file-system-access-restricted'
Returns:
eventEventdetailsObjectoriginstring - The origin that initiated access to the blocked path.isDirectoryboolean - Whether or not the path is a directory.pathstring - The blocked path attempting to be accessed.
callbackFunctionactionstring - The action to take as a result of the restricted path access attempt.allow- This will allowpathto be accessed despite restricted status.deny- This will block the access request and trigger anAbortError.tryAgain- This will open a new file picker and allow the user to choose another path.
const { app, dialog, BrowserWindow, session } = require('electron')
async function createWindow () {
const mainWindow = new BrowserWindow()
await mainWindow.loadURL('https://buzzfeed.com')
session.defaultSession.on('file-system-access-restricted', async (e, details, callback) => {
const { origin, path } = details
const { response } = await dialog.showMessageBox({
message: `Are you sure you want ${origin} to open restricted path ${path}?`,
title: 'File System Access Restricted',
buttons: ['Choose a different folder', 'Allow', 'Cancel'],
cancelId: 2
})
if (response === 0) {
callback('tryAgain')
} else if (response === 1) {
callback('allow')
} else {
callback('deny')
}
})
mainWindow.webContents.executeJavaScript(`
window.showDirectoryPicker({
id: 'electron-demo',
mode: 'readwrite',
startIn: 'downloads',
}).catch(e => {
console.log(e)
})`, true
)
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
Event: 'preconnect'
Returns:
eventEventpreconnectUrlstring - The URL being requested for preconnection by the renderer.allowCredentialsboolean - True if the renderer is requesting that the connection include credentials (see the spec for more details.)
Emitted when a render process requests preconnection to a URL, generally due to a resource hint.
Event: 'spellcheck-dictionary-initialized'
Returns:
eventEventlanguageCodestring - The language code of the dictionary file
Emitted when a hunspell dictionary file has been successfully initialized. This occurs after the file has been downloaded.
Event: 'spellcheck-dictionary-download-begin'
Returns:
eventEventlanguageCodestring - The language code of the dictionary file
Emitted when a hunspell dictionary file starts downloading
Event: 'spellcheck-dictionary-download-success'
Returns:
eventEventlanguageCodestring - The language code of the dictionary file
Emitted when a hunspell dictionary file has been successfully downloaded
Event: 'spellcheck-dictionary-download-failure'
Returns:
eventEventlanguageCodestring - The language code of the dictionary file
Emitted when a hunspell dictionary file download fails. For details on the failure you should collect a netlog and inspect the download request.
Event: 'select-hid-device'
Returns:
eventEventdetailsObjectdeviceListHIDDevice[]frameWebFrameMain | null - The frame initiating this event. May benullif accessed after the frame has either navigated or been destroyed.
callbackFunctiondeviceIdstring | null (optional)
Emitted when a HID device needs to be selected when a call to
navigator.hid.requestDevice is made. callback should be called with
deviceId to be selected; passing no arguments to callback will
cancel the request. Additionally, permissioning on navigator.hid can
be further managed by using ses.setPermissionCheckHandler(handler)
and ses.setDevicePermissionHandler(handler).
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'hid') {
// Add logic here to determine if permission should be given to allow HID selection
return true
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'hid') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.hid.requestDevice` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
}
return false
})
win.webContents.session.on('select-hid-device', (event, details, callback) => {
event.preventDefault()
const selectedDevice = details.deviceList.find((device) => {
return device.vendorId === 9025 && device.productId === 67
})
callback(selectedDevice?.deviceId)
})
})
Event: 'hid-device-added'
Returns:
eventEventdetailsObjectdeviceHIDDeviceframeWebFrameMain | null - The frame initiating this event. May benullif accessed after the frame has either navigated or been destroyed.
Emitted after navigator.hid.requestDevice has been called and
select-hid-device has fired if a new device becomes available before
the callback from select-hid-device is called. This event is intended for
use when using a UI to ask users to pick a device so that the UI can be updated
with the newly added device.
Event: 'hid-device-removed'
Returns:
eventEventdetailsObjectdeviceHIDDeviceframeWebFrameMain | null - The frame initiating this event. May benullif accessed after the frame has either navigated or been destroyed.
Emitted after navigator.hid.requestDevice has been called and
select-hid-device has fired if a device has been removed before the callback
from select-hid-device is called. This event is intended for use when using
a UI to ask users to pick a device so that the UI can be updated to remove the
specified device.
Event: 'hid-device-revoked'
Returns:
eventEventdetailsObjectdeviceHIDDeviceoriginstring (optional) - The origin that the device has been revoked from.
Emitted after HIDDevice.forget() has been called. This event can be used
to help maintain persistent storage of permissions when
setDevicePermissionHandler is used.
Event: 'select-serial-port'
Returns:
eventEventportListSerialPort[]webContentsWebContentscallbackFunctionportIdstring
Emitted when a serial port needs to be selected when a call to
navigator.serial.requestPort is made. callback should be called with
portId to be selected, passing an empty string to callback will
cancel the request. Additionally, permissioning on navigator.serial can
be managed by using ses.setPermissionCheckHandler(handler)
with the serial permission.
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow({
width: 800,
height: 600
})
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'serial') {
// Add logic here to determine if permission should be given to allow serial selection
return true
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'serial') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.serial.requestPort` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
}
return false
})
win.webContents.session.on('select-serial-port', (event, portList, webContents, callback) => {
event.preventDefault()
const selectedPort = portList.find((device) => {
return device.vendorId === '9025' && device.productId === '67'
})
if (!selectedPort) {
callback('')
} else {
callback(selectedPort.portId)
}
})
})
Event: 'serial-port-added'
Returns:
eventEventportSerialPortwebContentsWebContents
Emitted after navigator.serial.requestPort has been called and
select-serial-port has fired if a new serial port becomes available before
the callback from select-serial-port is called. This event is intended for
use when using a UI to ask users to pick a port so that the UI can be updated
with the newly added port.
Event: 'serial-port-removed'
Returns:
eventEventportSerialPortwebContentsWebContents
Emitted after navigator.serial.requestPort has been called and
select-serial-port has fired if a serial port has been removed before the
callback from select-serial-port is called. This event is intended for use
when using a UI to ask users to pick a port so that the UI can be updated
to remove the specified port.
Event: 'serial-port-revoked'
Returns:
eventEventdetailsObjectportSerialPortframeWebFrameMain | null - The frame initiating this event. May benullif accessed after the frame has either navigated or been destroyed.originstring - The origin that the device has been revoked from.
Emitted after SerialPort.forget() has been called. This event can be used
to help maintain persistent storage of permissions when setDevicePermissionHandler is used.
// Browser Process
const { app, BrowserWindow } = require('electron')
app.whenReady().then(() => {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.webContents.session.on('serial-port-revoked', (event, details) => {
console.log(`Access revoked for serial device from origin ${details.origin}`)
})
})
// Renderer Process
const portConnect = async () => {
// Request a port.
const port = await navigator.serial.requestPort()
// Wait for the serial port to open.
await port.open({ baudRate: 9600 })
// ...later, revoke access to the serial port.
await port.forget()
}
Event: 'select-usb-device'
Returns:
eventEventdetailsObjectdeviceListUSBDevice[]frameWebFrameMain | null - The frame initiating this event. May benullif accessed after the frame has either navigated or been destroyed.
callbackFunctiondeviceIdstring (optional)
Emitted when a USB device needs to be selected when a call to
navigator.usb.requestDevice is made. callback should be called with
deviceId to be selected; passing no arguments to callback will
cancel the request. Additionally, permissioning on navigator.usb can
be further managed by using ses.setPermissionCheckHandler(handler)
and ses.setDevicePermissionHandler(handler).
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'usb') {
// Add logic here to determine if permission should be given to allow USB selection
return true
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store (fetchGrantedDevices needs to be implemented by developer to fetch persisted permissions)
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'usb') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.usb.requestDevice` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
}
return false
})
win.webContents.session.on('select-usb-device', (event, details, callback) => {
event.preventDefault()
const selectedDevice = details.deviceList.find((device) => {
return device.vendorId === 9025 && device.productId === 67
})
if (selectedDevice) {
// Optionally, add this to the persisted devices (updateGrantedDevices needs to be implemented by developer to persist permissions)
grantedDevices.push(selectedDevice)
updateGrantedDevices(grantedDevices)
}
callback(selectedDevice?.deviceId)
})
})
Event: 'usb-device-added'
Returns:
eventEventdeviceUSBDevicewebContentsWebContents
Emitted after navigator.usb.requestDevice has been called and
select-usb-device has fired if a new device becomes available before
the callback from select-usb-device is called. This event is intended for
use when using a UI to ask users to pick a device so that the UI can be updated
with the newly added device.
Event: 'usb-device-removed'
Returns:
eventEventdeviceUSBDevicewebContentsWebContents
Emitted after navigator.usb.requestDevice has been called and
select-usb-device has fired if a device has been removed before the callback
from select-usb-device is called. This event is intended for use when using
a UI to ask users to pick a device so that the UI can be updated to remove the
specified device.
Event: 'usb-device-revoked'
Returns:
eventEventdetailsObjectdeviceUSBDeviceoriginstring (optional) - The origin that the device has been revoked from.
Emitted after USBDevice.forget() has been called. This event can be used
to help maintain persistent storage of permissions when
setDevicePermissionHandler is used.
Instance Methods
The following methods are available on instances of Session:
ses.getCacheSize()
Returns Promise<Integer> - the session's current cache size, in bytes.
ses.clearCache()
Returns Promise<void> - resolves when the cache clear operation is complete.
Clears the session’s HTTP cache.
ses.clearStorageData([options])
Returns Promise<void> - resolves when the storage data has been cleared.
ses.flushStorageData()
Writes any unwritten DOMStorage data to disk.
ses.setProxy(config)
configProxyConfig
Returns Promise<void> - Resolves when the proxy setting process is complete.
Sets the proxy settings.
You may need ses.closeAllConnections to close currently in flight connections to prevent
pooled sockets using previous proxy from being reused by future requests.
ses.resolveHost(host, [options])
hoststring - Hostname to resolve.
Returns Promise<ResolvedHost> - Resolves with the resolved IP addresses for the host.
ses.resolveProxy(url)
urlURL
Returns Promise<string> - Resolves with the proxy information for url.
ses.forceReloadProxyConfig()
Returns Promise<void> - Resolves when the all internal states of proxy service is reset and the latest proxy configuration is reapplied if it's already available. The pac script will be fetched from pacScript again if the proxy mode is pac_script.
ses.setDownloadPath(path)
pathstring - The download location.
Sets download saving directory. By default, the download directory will be the
Downloads under the respective app folder.
ses.enableNetworkEmulation(options)
Emulates network with the given configuration for the session.
const win = new BrowserWindow()
// To emulate a GPRS connection with 50kbps throughput and 500 ms latency.
win.webContents.session.enableNetworkEmulation({
latency: 500,
downloadThroughput: 6400,
uploadThroughput: 6400
})
// To emulate a network outage.
win.webContents.session.enableNetworkEmulation({ offline: true })
ses.preconnect(options)
Preconnects the given number of sockets to an origin.
ses.closeAllConnections()
Returns Promise<void> - Resolves when all connections are closed.
It will terminate / fail all requests currently in flight.
ses.fetch(input[, init])
inputstring | GlobalRequestinitRequestInit & { bypassCustomProtocolHandlers?: boolean } (optional)
Returns Promise<GlobalResponse> - see Response.
Sends a request, similarly to how fetch() works in the renderer, using
Chrome's network stack. This differs from Node's fetch(), which uses
Node.js's HTTP stack.
Example:
async function example () {
const response = await net.fetch('https://my.app')
if (response.ok) {
const body = await response.json()
// ... use the result.
}
}
See also net.fetch(), a convenience method which
issues requests from the default session.
See the MDN documentation for
fetch() for more
details.
Limitations:
net.fetch()does not support thedata:orblob:schemes.- The value of the
integrityoption is ignored. - The
.typeand.urlvalues of the returnedResponseobject are incorrect.
By default, requests made with net.fetch can be made to custom protocols
as well as file:, and will trigger webRequest handlers if present.
When the non-standard bypassCustomProtocolHandlers option is set in RequestInit,
custom protocol handlers will not be called for this request. This allows forwarding an
intercepted request to the built-in handler. webRequest
handlers will still be triggered when bypassing custom protocols.
protocol.handle('https', (req) => {
if (req.url === 'https://my-app.com') {
return new Response('<body>my app</body>')
} else {
return net.fetch(req, { bypassCustomProtocolHandlers: true })
}
})
ses.disableNetworkEmulation()
Disables any network emulation already active for the session. Resets to
the original network configuration.
ses.setCertificateVerifyProc(proc)
procFunction | nullrequestObjecthostnamestringcertificateCertificatevalidatedCertificateCertificateisIssuedByKnownRootboolean -trueif Chromium recognises the root CA as a standard root. If it isn't then it's probably the case that this certificate was generated by a MITM proxy whose root has been installed locally (for example, by a corporate proxy). This should not be trusted if theverificationResultis notOK.verificationResultstring -OKif the certificate is trusted, otherwise an error likeCERT_REVOKED.errorCodeInteger - Error code.
callbackFunctionverificationResultInteger - Value can be one of certificate error codes from here. Apart from the certificate error codes, the following special codes can be used.0- Indicates success and disables Certificate Transparency verification.-2- Indicates failure.-3- Uses the verification result from chromium.
Sets the certificate verify proc for session, the proc will be called with
proc(request, callback) whenever a server certificate
verification is requested. Calling callback(0) accepts the certificate,
calling callback(-2) rejects it.
Calling setCertificateVerifyProc(null) will revert back to default certificate
verify proc.
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.session.setCertificateVerifyProc((request, callback) => {
const { hostname } = request
if (hostname === 'github.com') {
callback(0)
} else {
callback(-2)
}
})
NOTE: The result of this procedure is cached by the network service.
ses.setPermissionRequestHandler(handler)
handlerFunction | nullwebContentsWebContents - WebContents requesting the permission. Please note that if the request comes from a subframe you should userequestingUrlto check the request origin.permissionstring - The type of requested permission.clipboard-read- Request access to read from the clipboard.clipboard-sanitized-write- Request access to write to the clipboard.display-capture- Request access to capture the screen via the Screen Capture API.fullscreen- Request control of the app's fullscreen state via the Fullscreen API.geolocation- Request access to the user's location via the Geolocation APIidle-detection- Request access to the user's idle state via the IdleDetector API.media- Request access to media devices such as camera, microphone and speakers.mediaKeySystem- Request access to DRM protected content.midi- Request MIDI access in the Web MIDI API.midiSysex- Request the use of system exclusive messages in the Web MIDI API.notifications- Request notification creation and the ability to display them in the user's system tray using the Notifications APIpointerLock- Request to directly interpret mouse movements as an input method via the Pointer Lock API. These requests always appear to originate from the main frame.keyboardLock- Request capture of keypresses for any or all of the keys on the physical keyboard via the Keyboard Lock API. These requests always appear to originate from the main frame.openExternal- Request to open links in external applications.speaker-selection- Request to enumerate and select audio output devices via the speaker-selection permissions policy.storage-access- Allows content loaded in a third-party context to request access to third-party cookies using the Storage Access API.top-level-storage-access- Allow top-level sites to request third-party cookie access on behalf of embedded content originating from another site in the same related website set using the Storage Access API.window-management- Request access to enumerate screens using thegetScreenDetailsAPI.unknown- An unrecognized permission request.fileSystem- Request access to read, write, and file management capabilities using the File System API.
callbackFunctionpermissionGrantedboolean - Allow or deny the permission.
detailsPermissionRequest | FilesystemPermissionRequest | MediaAccessPermissionRequest | OpenExternalPermissionRequest - Additional information about the permission being requested.
Sets the handler which can be used to respond to permission requests for the session.
Calling callback(true) will allow the permission and callback(false) will reject it.
To clear the handler, call setPermissionRequestHandler(null). Please note that
you must also implement setPermissionCheckHandler to get complete permission handling.
Most web APIs do a permission check and then make a permission request if the check is denied.
const { session } = require('electron')
session.fromPartition('some-partition').setPermissionRequestHandler((webContents, permission, callback) => {
if (webContents.getURL() === 'some-host' && permission === 'notifications') {
return callback(false) // denied.
}
callback(true)
})
ses.setPermissionCheckHandler(handler)
handlerFunction<boolean> | nullwebContents(WebContents | null) - WebContents checking the permission. Please note that if the request comes from a subframe you should userequestingUrlto check the request origin. All cross origin sub frames making permission checks will pass anullwebContents to this handler, while certain other permission checks such asnotificationschecks will always passnull. You should useembeddingOriginandrequestingOriginto determine what origin the owning frame and the requesting frame are on respectively.permissionstring - Type of permission check.clipboard-read- Request access to read from the clipboard.clipboard-sanitized-write- Request access to write to the clipboard.geolocation- Access the user's geolocation data via the Geolocation APIfullscreen- Control of the app's fullscreen state via the Fullscreen API.hid- Access the HID protocol to manipulate HID devices via the WebHID API.idle-detection- Access the user's idle state via the IdleDetector API.media- Access to media devices such as camera, microphone and speakers.mediaKeySystem- Access to DRM protected content.midi- Enable MIDI access in the Web MIDI API.midiSysex- Use system exclusive messages in the Web MIDI API.notifications- Configure and display desktop notifications to the user with the Notifications API.openExternal- Open links in external applications.pointerLock- Directly interpret mouse movements as an input method via the Pointer Lock API. These requests always appear to originate from the main frame.serial- Read from and write to serial devices with the Web Serial API.storage-access- Allows content loaded in a third-party context to request access to third-party cookies using the Storage Access API.top-level-storage-access- Allow top-level sites to request third-party cookie access on behalf of embedded content originating from another site in the same related website set using the Storage Access API.usb- Expose non-standard Universal Serial Bus (USB) compatible devices services to the web with the WebUSB API.deprecated-sync-clipboard-readDeprecated - Request access to rundocument.execCommand("paste")
requestingOriginstring - The origin URL of the permission checkdetailsObject - Some properties are only available on certain permission types.embeddingOriginstring (optional) - The origin of the frame embedding the frame that made the permission check. Only set for cross-origin sub frames making permission checks.securityOriginstring (optional) - The security origin of themediacheck.mediaTypestring (optional) - The type of media access being requested, can bevideo,audioorunknownrequestingUrlstring (optional) - The last URL the requesting frame loaded. This is not provided for cross-origin sub frames making permission checks.isMainFrameboolean - Whether the frame making the request is the main frame
Sets the handler which can be used to respond to permission checks for the session.
Returning true will allow the permission and false will reject it. Please note that
you must also implement setPermissionRequestHandler to get complete permission handling.
Most web APIs do a permission check and then make a permission request if the check is denied.
To clear the handler, call setPermissionCheckHandler(null).
const { session } = require('electron')
const url = require('node:url')
session.fromPartition('some-partition').setPermissionCheckHandler((webContents, permission, requestingOrigin) => {
if (new URL(requestingOrigin).hostname === 'some-host' && permission === 'notifications') {
return true // granted
}
return false // denied
})
ses.setDisplayMediaRequestHandler(handler[, opts])
handlerFunction | nullrequestObjectframeWebFrameMain | null - Frame that is requesting access to media. May benullif accessed after the frame has either navigated or been destroyed.securityOriginString - Origin of the page making the request.videoRequestedBoolean - true if the web content requested a video stream.audioRequestedBoolean - true if the web content requested an audio stream.userGestureBoolean - Whether a user gesture was active when this request was triggered.
callbackFunctionstreamsObjectvideoObject | WebFrameMain (optional)idString - The id of the stream being granted. This will usually come from a DesktopCapturerSource object.nameString - The name of the stream being granted. This will usually come from a DesktopCapturerSource object.
audioString | WebFrameMain (optional) - If a string is specified, can beloopbackorloopbackWithMute. Specifying a loopback device will capture system audio, and is currently only supported on Windows. If a WebFrameMain is specified, will capture audio from that frame.enableLocalEchoBoolean (optional) - Ifaudiois a WebFrameMain and this is set totrue, then local playback of audio will not be muted (e.g. usingMediaRecorderto recordWebFrameMainwith this flag set totruewill allow audio to pass through to the speakers while recording). Default isfalse.
optsObject (optional) macOS ExperimentaluseSystemPickerBoolean - true if the available native system picker should be used. Default isfalse. macOS Experimental
This handler will be called when web content requests access to display media
via the navigator.mediaDevices.getDisplayMedia API. Use the
desktopCapturer API to choose which stream(s) to grant
access to.
useSystemPicker allows an application to use the system picker instead of providing a specific video source from getSources.
This option is experimental, and currently available for MacOS 15+ only. If the system picker is available and useSystemPicker
is set to true, the handler will not be invoked.
const { session, desktopCapturer } = require('electron')
session.defaultSession.setDisplayMediaRequestHandler((request, callback) => {
desktopCapturer.getSources({ types: ['screen'] }).then((sources) => {
// Grant access to the first screen found.
callback({ video: sources[0] })
})
// Use the system picker if available.
// Note: this is currently experimental. If the system picker
// is available, it will be used and the media request handler
// will not be invoked.
}, { useSystemPicker: true })
Passing a WebFrameMain object as a video or audio stream will capture the video or audio stream from that frame.
const { session } = require('electron')
session.defaultSession.setDisplayMediaRequestHandler((request, callback) => {
// Allow the tab to capture itself.
callback({ video: request.frame })
})
Passing null instead of a function resets the handler to its default state.
ses.setDevicePermissionHandler(handler)
handlerFunction<boolean> | nulldetailsObjectdeviceTypestring - The type of device that permission is being requested on, can behid,serial, orusb.originstring - The origin URL of the device permission check.deviceHIDDevice | SerialPort | USBDevice - the device that permission is being requested for.
Sets the handler which can be used to respond to device permission checks for the session.
Returning true will allow the device to be permitted and false will reject it.
To clear the handler, call setDevicePermissionHandler(null).
This handler can be used to provide default permissioning to devices without first calling for permission
to devices (eg via navigator.hid.requestDevice). If this handler is not defined, the default device
permissions as granted through device selection (eg via navigator.hid.requestDevice) will be used.
Additionally, the default behavior of Electron is to store granted device permission in memory.
If longer term storage is needed, a developer can store granted device
permissions (eg when handling the select-hid-device event) and then read from that storage with setDevicePermissionHandler.
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'hid') {
// Add logic here to determine if permission should be given to allow HID selection
return true
} else if (permission === 'serial') {
// Add logic here to determine if permission should be given to allow serial port selection
} else if (permission === 'usb') {
// Add logic here to determine if permission should be given to allow USB device selection
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'hid') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.hid.requestDevice` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
} else if (details.deviceType === 'serial') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.hid.requestDevice` first)
return true
}
}
return false
})
win.webContents.session.on('select-hid-device', (event, details, callback) => {
event.preventDefault()
const selectedDevice = details.deviceList.find((device) => {
return device.vendorId === 9025 && device.productId === 67
})
callback(selectedDevice?.deviceId)
})
})
ses.setUSBProtectedClassesHandler(handler)
handlerFunction<string[]> | nulldetailsObjectprotectedClassesstring[] - The current list of protected USB classes. Possible class values include:audioaudio-videohidmass-storagesmart-cardvideowireless
Sets the handler which can be used to override which USB classes are protected. The return value for the handler is a string array of USB classes which should be considered protected (eg not available in the renderer). Valid values for the array are:
audioaudio-videohidmass-storagesmart-cardvideowireless
Returning an empty string array from the handler will allow all USB classes; returning the passed in array will maintain the default list of protected USB classes (this is also the default behavior if a handler is not defined).
To clear the handler, call setUSBProtectedClassesHandler(null).
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.webContents.session.setUSBProtectedClassesHandler((details) => {
// Allow all classes:
// return []
// Keep the current set of protected classes:
// return details.protectedClasses
// Selectively remove classes:
return details.protectedClasses.filter((usbClass) => {
// Exclude classes except for audio classes
return usbClass.indexOf('audio') === -1
})
})
})
ses.setBluetoothPairingHandler(handler) Windows Linux
handlerFunction | nulldetailsObjectdeviceIdstringpairingKindstring - The type of pairing prompt being requested. One of the following values:confirmThis prompt is requesting confirmation that the Bluetooth device should be paired.confirmPinThis prompt is requesting confirmation that the provided PIN matches the pin displayed on the device.providePinThis prompt is requesting that a pin be provided for the device.
frameWebFrameMain | null - The frame initiating this handler. May benullif accessed after the frame has either navigated or been destroyed.pinstring (optional) - The pin value to verify ifpairingKindisconfirmPin.
callbackFunctionresponseObjectconfirmedboolean -falseshould be passed in if the dialog is canceled. If thepairingKindisconfirmorconfirmPin, this value should indicate if the pairing is confirmed. If thepairingKindisprovidePinthe value should betruewhen a value is provided.pinstring | null (optional) - When thepairingKindisprovidePinthis value should be the required pin for the Bluetooth device.
Sets a handler to respond to Bluetooth pairing requests. This handler
allows developers to handle devices that require additional validation
before pairing. When a handler is not defined, any pairing on Linux or Windows
that requires additional validation will be automatically cancelled.
macOS does not require a handler because macOS handles the pairing
automatically. To clear the handler, call setBluetoothPairingHandler(null).
const { app, BrowserWindow, session } = require('electron')
const path = require('node:path')
function createWindow () {
let bluetoothPinCallback = null
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
mainWindow.webContents.session.setBluetoothPairingHandler((details, callback) => {
bluetoothPinCallback = callback
// Send a IPC message to the renderer to prompt the user to confirm the pairing.
// Note that this will require logic in the renderer to handle this message and
// display a prompt to the user.
mainWindow.webContents.send('bluetooth-pairing-request', details)
})
// Listen for an IPC message from the renderer to get the response for the Bluetooth pairing.
mainWindow.webContents.ipc.on('bluetooth-pairing-response', (event, response) => {
bluetoothPinCallback(response)
})
}
app.whenReady().then(() => {
createWindow()
})
ses.clearHostResolverCache()
Returns Promise<void> - Resolves when the operation is complete.
Clears the host resolver cache.
ses.allowNTLMCredentialsForDomains(domains)
domainsstring - A comma-separated list of servers for which integrated authentication is enabled.
Dynamically sets whether to always send credentials for HTTP NTLM or Negotiate authentication.
const { session } = require('electron')
// consider any url ending with `example.com`, `foobar.com`, `baz`
// for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*example.com, *foobar.com, *baz')
// consider all urls for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*')
ses.setUserAgent(userAgent[, acceptLanguages])
userAgentstringacceptLanguagesstring (optional)
Overrides the userAgent and acceptLanguages for this session.
The acceptLanguages must a comma separated ordered list of language codes, for
example "en-US,fr,de,ko,zh-CN,ja".
This doesn't affect existing WebContents, and each WebContents can use
webContents.setUserAgent to override the session-wide user agent.
ses.isPersistent()
Returns boolean - Whether or not this session is a persistent one. The default
webContents session of a BrowserWindow is persistent. When creating a session
from a partition, session prefixed with persist: will be persistent, while others
will be temporary.
ses.getUserAgent()
Returns string - The user agent for this session.
ses.setSSLConfig(config)
configObjectminVersionstring (optional) - Can betls1,tls1.1,tls1.2ortls1.3. The minimum SSL version to allow when connecting to remote servers. Defaults totls1.maxVersionstring (optional) - Can betls1.2ortls1.3. The maximum SSL version to allow when connecting to remote servers. Defaults totls1.3.disabledCipherSuitesInteger[] (optional) - List of cipher suites which should be explicitly prevented from being used in addition to those disabled by the net built-in policy. Supported literal forms: 0xAABB, where AA iscipher_suite[0]and BB iscipher_suite[1], as defined in RFC 2246, Section 7.4.1.2. Unrecognized but parsable cipher suites in this form will not return an error. Ex: To disable TLS_RSA_WITH_RC4_128_MD5, specify 0x0004, while to disable TLS_ECDH_ECDSA_WITH_RC4_128_SHA, specify 0xC002. Note that TLSv1.3 ciphers cannot be disabled using this mechanism.
Sets the SSL configuration for the session. All subsequent network requests will use the new configuration. Existing network connections (such as WebSocket connections) will not be terminated, but old sockets in the pool will not be reused for new connections.
ses.getBlobData(identifier)
identifierstring - Valid UUID.
Returns Promise<Buffer> - resolves with blob data.
ses.downloadURL(url[, options])
urlstring
Initiates a download of the resource at url.
The API will generate a DownloadItem that can be accessed
with the will-download event.
This does not perform any security checks that relate to a page's origin,
unlike webContents.downloadURL.
ses.createInterruptedDownload(options)
Allows resuming cancelled or interrupted downloads from previous Session.
The API will generate a DownloadItem that can be accessed with the will-download
event. The DownloadItem will not have any WebContents associated with it and
the initial state will be interrupted. The download will start only when the
resume API is called on the DownloadItem.
ses.clearAuthCache()
Returns Promise<void> - resolves when the session’s HTTP authentication cache has been cleared.
ses.setPreloads(preloads) Deprecated
preloadsstring[] - An array of absolute path to preload scripts
Adds scripts that will be executed on ALL web contents that are associated with
this session just before normal preload scripts run.
Deprecated: Use the new ses.registerPreloadScript API.
ses.getPreloads() Deprecated
Returns string[] an array of paths to preload scripts that have been
registered.
Deprecated: Use the new ses.getPreloadScripts API. This will only return preload script paths
for frame context types.
ses.registerPreloadScript(script)
scriptPreloadScriptRegistration - Preload script
Registers preload script that will be executed in its associated context type in this session. For
frame contexts, this will run prior to any preload defined in the web preferences of a
WebContents.
Returns string - The ID of the registered preload script.
ses.unregisterPreloadScript(id)
idstring - Preload script ID
Unregisters script.
ses.getPreloadScripts()
Returns PreloadScript[]: An array of paths to preload scripts that have been registered.
ses.setCodeCachePath(path)
pathString - Absolute path to store the v8 generated JS code cache from the renderer.
Sets the directory to store the generated JS code cache for this session. The directory is not required to be created by the user before this call, the runtime will create if it does not exist otherwise will use the existing directory. If directory cannot be created, then code cache will not be used and all operations related to code cache will fail silently inside the runtime. By default, the directory will be Code Cache under the
respective user data folder.
Note that by default code cache is only enabled for http(s) URLs, to enable code
cache for custom protocols, codeCache: true and standard: true must be
specified when registering the protocol.
ses.clearCodeCaches(options)
Returns Promise<void> - resolves when the code cache clear operation is complete.
ses.getSharedDictionaryUsageInfo()
Returns Promise<SharedDictionaryUsageInfo[]> - an array of shared dictionary information entries in Chromium's networking service's storage.
Shared dictionaries are used to power advanced compression of data sent over the wire, specifically with Brotli and ZStandard. You don't need to call any of the shared dictionary APIs in Electron to make use of this advanced web feature, but if you do, they allow deeper control and inspection of the shared dictionaries used during decompression.
To get detailed information about a specific shared dictionary entry, call getSharedDictionaryInfo(options).
ses.getSharedDictionaryInfo(options)
Returns Promise<SharedDictionaryInfo[]> - an array of shared dictionary information entries in Chromium's networking service's storage.
To get information about all present shared dictionaries, call getSharedDictionaryUsageInfo().
ses.clearSharedDictionaryCache()
Returns Promise<void> - resolves when the dictionary cache has been cleared, both in memory and on disk.
ses.clearSharedDictionaryCacheForIsolationKey(options)
Returns Promise<void> - resolves when the dictionary cache has been cleared for the specified isolation key, both in memory and on disk.
ses.setSpellCheckerEnabled(enable)
enableboolean
Sets whether to enable the builtin spell checker.
ses.isSpellCheckerEnabled()
Returns boolean - Whether the builtin spell checker is enabled.
ses.setSpellCheckerLanguages(languages)
languagesstring[] - An array of language codes to enable the spellchecker for.
The built in spellchecker does not automatically detect what language a user is typing in. In order for the
spell checker to correctly check their words you must call this API with an array of language codes. You can
get the list of supported language codes with the ses.availableSpellCheckerLanguages property.
On macOS, the OS spellchecker is used and will detect your language automatically. This API is a no-op on macOS.
ses.getSpellCheckerLanguages()
Returns string[] - An array of language codes the spellchecker is enabled for. If this list is empty the spellchecker
will fallback to using en-US. By default on launch if this setting is an empty list Electron will try to populate this
setting with the current OS locale. This setting is persisted across restarts.
On macOS, the OS spellchecker is used and has its own list of languages. On macOS, this API will return whichever languages have been configured by the OS.
ses.setSpellCheckerDictionaryDownloadURL(url)
urlstring - A base URL for Electron to download hunspell dictionaries from.
By default Electron will download hunspell dictionaries from the Chromium CDN. If you want to override this
behavior you can use this API to point the dictionary downloader at your own hosted version of the hunspell
dictionaries. We publish a hunspell_dictionaries.zip file with each release which contains the files you need
to host here.
The file server must be case insensitive. If you cannot do this, you must upload each file twice: once with the case it has in the ZIP file and once with the filename as all lowercase.
If the files present in hunspell_dictionaries.zip are available at https://example.com/dictionaries/language-code.bdic
then you should call this api with ses.setSpellCheckerDictionaryDownloadURL('https://example.com/dictionaries/'). Please
note the trailing slash. The URL to the dictionaries is formed as ${url}${filename}.
On macOS, the OS spellchecker is used and therefore we do not download any dictionary files. This API is a no-op on macOS.
ses.listWordsInSpellCheckerDictionary()
Returns Promise<string[]> - An array of all words in app's custom dictionary.
Resolves when the full dictionary is loaded from disk.
ses.addWordToSpellCheckerDictionary(word)
wordstring - The word you want to add to the dictionary
Returns boolean - Whether the word was successfully written to the custom dictionary. This API
will not work on non-persistent (in-memory) sessions.
On macOS and Windows, this word will be written to the OS custom dictionary as well.
ses.removeWordFromSpellCheckerDictionary(word)
wordstring - The word you want to remove from the dictionary
Returns boolean - Whether the word was successfully removed from the custom dictionary. This API
will not work on non-persistent (in-memory) sessions.
On macOS and Windows, this word will be removed from the OS custom dictionary as well.
ses.loadExtension(path[, options]) Deprecated
pathstring - Path to a directory containing an unpacked Chrome extension
Returns Promise<Extension> - resolves when the extension is loaded.
This method will raise an exception if the extension could not be loaded. If there are warnings when installing the extension (e.g. if the extension requests an API that Electron does not support) then they will be logged to the console.
Note that Electron does not support the full range of Chrome extensions APIs. See Supported Extensions APIs for more details on what is supported.
Note that in previous versions of Electron, extensions that were loaded would
be remembered for future runs of the application. This is no longer the case:
loadExtension must be called on every boot of your app if you want the
extension to be loaded.
const { app, session } = require('electron')
const path = require('node:path')
app.whenReady().then(async () => {
await session.defaultSession.loadExtension(
path.join(__dirname, 'react-devtools'),
// allowFileAccess is required to load the devtools extension on file:// URLs.
{ allowFileAccess: true }
)
// Note that in order to use the React DevTools extension, you'll need to
// download and unzip a copy of the extension.
})
This API does not support loading packed (.crx) extensions.
This API cannot be called before the ready event of the app module
is emitted.
Loading extensions into in-memory (non-persistent) sessions is not supported and will throw an error.
Deprecated: Use the new ses.extensions.loadExtension API.
ses.removeExtension(extensionId) Deprecated
extensionIdstring - ID of extension to remove
Unloads an extension.
This API cannot be called before the ready event of the app module
is emitted.
Deprecated: Use the new ses.extensions.removeExtension API.
ses.getExtension(extensionId) Deprecated
extensionIdstring - ID of extension to query
Returns Extension | null - The loaded extension with the given ID.
This API cannot be called before the ready event of the app module
is emitted.
Deprecated: Use the new ses.extensions.getExtension API.
ses.getAllExtensions() Deprecated
Returns Extension[] - A list of all loaded extensions.
This API cannot be called before the ready event of the app module
is emitted.
Deprecated: Use the new ses.extensions.getAllExtensions API.
ses.getStoragePath()
Returns string | null - The absolute file system path where data for this
session is persisted on disk. For in memory sessions this returns null.
ses.clearData([options])
Returns Promise<void> - resolves when all data has been cleared.
Clears various different types of data.
This method clears more types of data and is more thorough than the
clearStorageData method.
Cookies are stored at a broader scope than origins. When removing cookies and filtering by origins (or excludeOrigins), the cookies will be removed at the registrable domain level. For example, clearing cookies for the origin https://really.specific.origin.example.com/ will end up clearing all cookies for example.com. Clearing cookies for the origin https://my.website.example.co.uk/ will end up clearing all cookies for example.co.uk.
Clearing cache data will also clear the shared dictionary cache. This means that any dictionaries used for compression may be reloaded after clearing the cache. If you wish to clear the shared dictionary cache but leave other cached data intact, you may want to use the clearSharedDictionaryCache method.
For more information, refer to Chromium's BrowsingDataRemover interface.
Instance Properties
The following properties are available on instances of Session:
ses.availableSpellCheckerLanguages Readonly
A string[] array which consists of all the known available spell checker languages. Providing a language
code to the setSpellCheckerLanguages API that isn't in this array will result in an error.
ses.spellCheckerEnabled
A boolean indicating whether builtin spell checker is enabled.
ses.storagePath Readonly
A string | null indicating the absolute file system path where data for this
session is persisted on disk. For in memory sessions this returns null.
ses.cookies Readonly
A Cookies object for this session.
ses.extensions Readonly
A Extensions object for this session.
ses.serviceWorkers Readonly
A ServiceWorkers object for this session.
ses.webRequest Readonly
A WebRequest object for this session.
ses.protocol Readonly
A Protocol object for this session.
const { app, session } = require('electron')
const path = require('node:path')
app.whenReady().then(() => {
const protocol = session.fromPartition('some-partition').protocol
if (!protocol.registerFileProtocol('atom', (request, callback) => {
const url = request.url.substr(7)
callback({ path: path.normalize(path.join(__dirname, url)) })
})) {
console.error('Failed to register protocol')
}
})
ses.netLog Readonly
A NetLog object for this session.
const { app, session } = require('electron')
app.whenReady().then(async () => {
const netLog = session.fromPartition('some-partition').netLog
netLog.startLogging('/path/to/net-log')
// After some network events
const path = await netLog.stopLogging()
console.log('Net-logs written to', path)
})