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')
let win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('http://github.com')
const ses = win.webContents.session
console.log(ses.getUserAgent())
The session
module has the following methods:
partition
Stringoptions
Object (optional)cache
Boolean - Whether to enable cache.
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.
The session
module has the following properties:
A Session
object, the default session object of the app.
Get and set properties of a session.
Process: Main
You can create a Session
object in the session
module:
const { session } = require('electron')
const ses = session.fromPartition('persist:name')
console.log(ses.getUserAgent())
The following events are available on instances of Session
:
Returns:
event
Eventitem
DownloadItemwebContents
WebContents
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('request')(item.getURL(), (data) => {
require('fs').writeFileSync('/somewhere', data)
})
})
Returns:
event
EventpreconnectUrl
String - The URL being requested for preconnection by the renderer.allowCredentials
Boolean - 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.
Returns:
event
EventlanguageCode
String - 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.
Returns:
event
EventlanguageCode
String - The language code of the dictionary file
Emitted when a hunspell dictionary file starts downloading
Returns:
event
EventlanguageCode
String - The language code of the dictionary file
Emitted when a hunspell dictionary file has been successfully downloaded
Returns:
event
EventlanguageCode
String - 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.
The following methods are available on instances of Session
:
Returns Promise<Integer>
- the session's current cache size, in bytes.
Returns Promise<void>
- resolves when the cache clear operation is complete.
Clears the session’s HTTP cache.
options
Object (optional)origin
String (optional) - Should followwindow.location.origin
’s representationscheme://host:port
.storages
String[] (optional) - The types of storages to clear, can contain:appcache
,cookies
,filesystem
,indexdb
,localstorage
,shadercache
,websql
,serviceworkers
,cachestorage
. If not specified, clear all storage types.quotas
String[] (optional) - The types of quotas to clear, can contain:temporary
,persistent
,syncable
. If not specified, clear all quotas.
Returns Promise<void>
- resolves when the storage data has been cleared.
Writes any unwritten DOMStorage data to disk.
config
ObjectpacScript
String (optional) - The URL associated with the PAC file.proxyRules
String (optional) - Rules indicating which proxies to use.proxyBypassRules
String (optional) - Rules indicating which URLs should bypass the proxy settings.
Returns Promise<void>
- Resolves when the proxy setting process is complete.
Sets the proxy settings.
When pacScript
and proxyRules
are provided together, the proxyRules
option is ignored and pacScript
configuration is applied.
The proxyRules
has to follow the rules below:
proxyRules = schemeProxies[";"<schemeProxies>]
schemeProxies = [<urlScheme>"="]<proxyURIList>
urlScheme = "http" | "https" | "ftp" | "socks"
proxyURIList = <proxyURL>[","<proxyURIList>]
proxyURL = [<proxyScheme>"://"]<proxyHost>[":"<proxyPort>]
For example:
http=foopy:80;ftp=foopy2
- Use HTTP proxyfoopy:80
forhttp://
URLs, and HTTP proxyfoopy2:80
forftp://
URLs.foopy:80
- Use HTTP proxyfoopy:80
for all URLs.foopy:80,bar,direct://
- Use HTTP proxyfoopy:80
for all URLs, failing over tobar
iffoopy:80
is unavailable, and after that using no proxy.socks4://foopy
- Use SOCKS v4 proxyfoopy:1080
for all URLs.http=foopy,socks5://bar.com
- Use HTTP proxyfoopy
for http URLs, and fail over to the SOCKS5 proxybar.com
iffoopy
is unavailable.http=foopy,direct://
- Use HTTP proxyfoopy
for http URLs, and use no proxy iffoopy
is unavailable.http=foopy;socks=foopy2
- Use HTTP proxyfoopy
for http URLs, and usesocks4://foopy2
for all other URLs.
The proxyBypassRules
is a comma separated list of rules described below:
-
[ URL_SCHEME "://" ] HOSTNAME_PATTERN [ ":" <port> ]
Match all hostnames that match the pattern HOSTNAME_PATTERN.
Examples: "foobar.com", "foobar.com", ".foobar.com", "*foobar.com:99", "https://x.*.y.com:99"
-
"." HOSTNAME_SUFFIX_PATTERN [ ":" PORT ]
Match a particular domain suffix.
Examples: ".google.com", ".com", "http://.google.com"
-
[ SCHEME "://" ] IP_LITERAL [ ":" PORT ]
Match URLs which are IP address literals.
Examples: "127.0.1", "[0:0::1]", "[::1]", "http://[::1]:99"
-
IP_LITERAL "/" PREFIX_LENGTH_IN_BITS
Match any URL that is to an IP literal that falls between the given range. IP range is specified using CIDR notation.
Examples: "192.168.1.1/16", "fefe:13::abc/33".
-
<local>
Match local addresses. The meaning of
<local>
is whether the host matches one of: "127.0.0.1", "::1", "localhost".
url
URL
Returns Promise<String>
- Resolves with the proxy information for url
.
path
String - The download location.
Sets download saving directory. By default, the download directory will be the
Downloads
under the respective app folder.
options
Objectoffline
Boolean (optional) - Whether to emulate network outage. Defaults to false.latency
Double (optional) - RTT in ms. Defaults to 0 which will disable latency throttling.downloadThroughput
Double (optional) - Download rate in Bps. Defaults to 0 which will disable download throttling.uploadThroughput
Double (optional) - Upload rate in Bps. Defaults to 0 which will disable upload throttling.
Emulates network with the given configuration for the session
.
// To emulate a GPRS connection with 50kbps throughput and 500 ms latency.
window.webContents.session.enableNetworkEmulation({
latency: 500,
downloadThroughput: 6400,
uploadThroughput: 6400
})
// To emulate a network outage.
window.webContents.session.enableNetworkEmulation({ offline: true })
options
Objecturl
String - URL for preconnect. Only the origin is relevant for opening the socket.numSockets
Number (optional) - number of sockets to preconnect. Must be between 1 and 6. Defaults to 1.
Preconnects the given number of sockets to an origin.
Disables any network emulation already active for the session
. Resets to
the original network configuration.
proc
Function | nullrequest
Objecthostname
Stringcertificate
CertificatevalidatedCertificate
CertificateverificationResult
String - Verification result from chromium.errorCode
Integer - Error code.
callback
FunctionverificationResult
Integer - 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')
let win = new BrowserWindow()
win.webContents.session.setCertificateVerifyProc((request, callback) => {
const { hostname } = request
if (hostname === 'github.com') {
callback(0)
} else {
callback(-2)
}
})
handler
Function | nullwebContents
WebContents - WebContents requesting the permission. Please note that if the request comes from a subframe you should userequestingUrl
to check the request origin.permission
String - Enum of 'media', 'geolocation', 'notifications', 'midiSysex', 'pointerLock', 'fullscreen', 'openExternal'.callback
FunctionpermissionGranted
Boolean - Allow or deny the permission.
details
Object - Some properties are only available on certain permission types.externalURL
String (optional) - The url of theopenExternal
request.mediaTypes
String[] (optional) - The types of media access being requested, elements can bevideo
oraudio
requestingUrl
String - The last URL the requesting frame loadedisMainFrame
Boolean - Whether the frame making the request is the main frame
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)
.
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)
})
handler
Function | nullwebContents
WebContents - WebContents checking the permission. Please note that if the request comes from a subframe you should userequestingUrl
to check the request origin.permission
String - Enum of 'media'.requestingOrigin
String - The origin URL of the permission checkdetails
Object - Some properties are only available on certain permission types.securityOrigin
String - The security orign of themedia
check.mediaType
String - The type of media access being requested, can bevideo
,audio
orunknown
requestingUrl
String - The last URL the requesting frame loadedisMainFrame
Boolean - 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.
To clear the handler, call setPermissionCheckHandler(null)
.
const { session } = require('electron')
session.fromPartition('some-partition').setPermissionCheckHandler((webContents, permission) => {
if (webContents.getURL() === 'some-host' && permission === 'notifications') {
return false // denied
}
return true
})
Returns Promise<void>
- Resolves when the operation is complete.
Clears the host resolver cache.
domains
String - 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('*')
userAgent
StringacceptLanguages
String (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.
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.
Returns String
- The user agent for this session.
identifier
String - Valid UUID.
Returns Promise<Buffer>
- resolves with blob data.
url
String
Initiates a download of the resource at url
.
The API will generate a DownloadItem that can be accessed
with the will-download event.
Note: This does not perform any security checks that relate to a page's origin,
unlike webContents.downloadURL
.
options
Objectpath
String - Absolute path of the download.urlChain
String[] - Complete URL chain for the download.mimeType
String (optional)offset
Integer - Start range for the download.length
Integer - Total length of the download.lastModified
String (optional) - Last-Modified header value.eTag
String (optional) - ETag header value.startTime
Double (optional) - Time when download was started in number of seconds since UNIX epoch.
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.
Returns Promise<void>
- resolves when the session’s HTTP authentication cache has been cleared.
preloads
String[] - 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.
Returns String[]
an array of paths to preload scripts that have been
registered.
languages
String[] - 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.
Note: On macOS the OS spellchecker is used and will detect your language automatically. This API is a no-op on macOS.
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.
Note: On macOS the OS spellchecker is used and has it's own list of languages. This API is a no-op on macOS.
url
String - 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 you must upload each file twice, once with the case it
has in the ZIP file and once with the filename as all lower case.
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}
.
Note: On macOS the OS spellchecker is used and therefore we do not download any dictionary files. This API is a no-op on macOS.
Returns Promise<String[]>
- An array of all words in app's custom dictionary.
Resolves when the full dictionary is loaded from disk.
word
String - 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.
Note: On macOS and Windows 10 this word will be written to the OS custom dictionary as well
word
String - 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.
Note: On macOS and Windows 10 this word will be removed from the OS custom dictionary as well
path
String - 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('path')
app.on('ready', async () => {
await session.defaultSession.loadExtension(path.join(__dirname, 'react-devtools'))
// 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.
Note: This API cannot be called before the ready
event of the app
module
is emitted.
Note: Loading extensions into in-memory (non-persistent) sessions is not supported and will throw an error.
extensionId
String - ID of extension to remove
Unloads an extension.
Note: This API cannot be called before the ready
event of the app
module
is emitted.
extensionId
String - ID of extension to query
Returns Extension
| null
- The loaded extension with the given ID.
Note: This API cannot be called before the ready
event of the app
module
is emitted.
Returns Extension[]
- A list of all loaded extensions.
Note: This API cannot be called before the ready
event of the app
module
is emitted.
The following properties are available on instances of Session
:
A String[]
array which consists of all the known available spell checker languages. Providing a language
code to the setSpellCheckerLanaguages
API that isn't in this array will result in an error.
A Cookies
object for this session.
A ServiceWorkers
object for this session.
A WebRequest
object for this session.
A Protocol
object for this session.
const { app, session } = require('electron')
const path = require('path')
app.whenReady().then(() => {
const protocol = session.fromPartition('some-partition').protocol
protocol.registerFileProtocol('atom', (request, callback) => {
let url = request.url.substr(7)
callback({ path: path.normalize(`${__dirname}/${url}`) })
}, (error) => {
if (error) console.error('Failed to register protocol')
})
})
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)
})