client-request.md

Class: ClientRequest

Make HTTP/HTTPS requests.

Process: Main, Utility
This class is not exported from the 'electron' module. It is only available as a return value of other methods in the Electron API.

ClientRequest implements the Writable Stream interface and is therefore an EventEmitter.

new ClientRequest(options)

• options (Object | string) - If options is a string, it is interpreted as the request URL. If it is an object, it is expected to fully specify an HTTP request via the following properties:
  • method string (optional) - The HTTP request method. Defaults to the GET method.
  • url string (optional) - The request URL. Must be provided in the absolute form with the protocol scheme specified as http or https.
  • headers Record<string, string | string[]> (optional) - Headers to be sent with the request.
  • session Session (optional) - The Session instance with which the request is associated.
  • partition string (optional) - The name of the partition with which the request is associated. Defaults to the empty string. The session option supersedes partition. Thus if a session is explicitly specified, partition is ignored.
  • credentials string (optional) - Can be include, omit or same-origin. Whether to send credentials with this request. If set to include, credentials from the session associated with the request will be used. If set to omit, credentials will not be sent with the request (and the 'login' event will not be triggered in the event of a 401). If set to same-origin, origin must also be specified. This matches the behavior of the fetch option of the same name. If this option is not specified, authentication data from the session will be sent, and cookies will not be sent (unless useSessionCookies is set).
  • useSessionCookies boolean (optional) - Whether to send cookies with this request from the provided session. If credentials is specified, this option has no effect. Default is false.
  • protocol string (optional) - Can be http: or https:. The protocol scheme in the form 'scheme:'. Defaults to 'http:'.
  • host string (optional) - The server host provided as a concatenation of the hostname and the port number 'hostname:port'.
  • hostname string (optional) - The server host name.
  • port Integer (optional) - The server's listening port number.
  • path string (optional) - The path part of the request URL.
  • redirect string (optional) - Can be follow, error or manual. The redirect mode for this request. When mode is error, any redirection will be aborted. When mode is manual the redirection will be cancelled unless request.followRedirect is invoked synchronously during the redirect event. Defaults to follow.
  • origin string (optional) - The origin URL of the request.
  • referrerPolicy string (optional) - can be "", no-referrer, no-referrer-when-downgrade, origin, origin-when-cross-origin, unsafe-url, same-origin, strict-origin, or strict-origin-when-cross-origin. Defaults to strict-origin-when-cross-origin.
  • cache string (optional) - can be default, no-store, reload, no-cache, force-cache or only-if-cached.

options properties such as protocol, host, hostname, port and path strictly follow the Node.js model as described in the URL module.

For instance, we could have created the same request to 'github.com' as follows:

const request = net.request({
  method: 'GET',
  protocol: 'https:',
  hostname: 'github.com',
  port: 443,
  path: '/'
})

Instance Events

Event: 'response'

Returns:

• response IncomingMessage - An object representing the HTTP response message.

Event: 'login'

Returns:

• authInfo Object
  • isProxy boolean
  • scheme string
  • host string
  • port Integer
  • realm string
• callback Function
  • username string (optional)
  • password string (optional)

Emitted when an authenticating proxy is asking for user credentials.

The callback function is expected to be called back with user credentials:

• username string
• password string

request.on('login', (authInfo, callback) => {
  callback('username', 'password')
})

Providing empty credentials will cancel the request and report an authentication error on the response object:

request.on('response', (response) => {
  console.log(`STATUS: ${response.statusCode}`)
  response.on('error', (error) => {
    console.log(`ERROR: ${JSON.stringify(error)}`)
  })
})
request.on('login', (authInfo, callback) => {
  callback()
})

Event: 'finish'

Emitted just after the last chunk of the request's data has been written into the request object.

Event: 'abort'

Emitted when the request is aborted. The abort event will not be fired if the request is already closed.

Event: 'error'

Returns:

• error Error - an error object providing some information about the failure.

Emitted when the net module fails to issue a network request. Typically when the request object emits an error event, a close event will subsequently follow and no response object will be provided.

Event: 'close'

Emitted as the last event in the HTTP request-response transaction. The close event indicates that no more events will be emitted on either the request or response objects.

Event: 'redirect'

Returns:

• statusCode Integer
• method string
• redirectUrl string
• responseHeaders Record<string, string[]>

Emitted when the server returns a redirect response (e.g. 301 Moved Permanently). Calling request.followRedirect will continue with the redirection. If this event is handled, request.followRedirect must be called synchronously, otherwise the request will be cancelled.

Instance Properties

request.chunkedEncoding

A boolean specifying whether the request will use HTTP chunked transfer encoding or not. Defaults to false. The property is readable and writable, however it can be set only before the first write operation as the HTTP headers are not yet put on the wire. Trying to set the chunkedEncoding property after the first write will throw an error.

Using chunked encoding is strongly recommended if you need to send a large request body as data will be streamed in small chunks instead of being internally buffered inside Electron process memory.

Instance Methods

request.setHeader(name, value)

• name string - An extra HTTP header name.
• value string - An extra HTTP header value.

Adds an extra HTTP header. The header name will be issued as-is without lowercasing. It can be called only before first write. Calling this method after the first write will throw an error. If the passed value is not a string, its toString() method will be called to obtain the final value.

Certain headers are restricted from being set by apps. These headers are listed below. More information on restricted headers can be found in Chromium's header utils.

• Content-Length
• Host
• Trailer or Te
• Upgrade
• Cookie2
• Keep-Alive
• Transfer-Encoding

Additionally, setting the Connection header to the value upgrade is also disallowed.

request.getHeader(name)

• name string - Specify an extra header name.

Returns string - The value of a previously set extra header name.

request.removeHeader(name)

• name string - Specify an extra header name.

Removes a previously set extra header name. This method can be called only before first write. Trying to call it after the first write will throw an error.

request.write(chunk[, encoding][, callback])

• chunk (string | Buffer) - A chunk of the request body's data. If it is a string, it is converted into a Buffer using the specified encoding.
• encoding string (optional) - Used to convert string chunks into Buffer objects. Defaults to 'utf-8'.
• callback Function (optional) - Called after the write operation ends.

callback is essentially a dummy function introduced in the purpose of keeping similarity with the Node.js API. It is called asynchronously in the next tick after chunk content have been delivered to the Chromium networking layer. Contrary to the Node.js implementation, it is not guaranteed that chunk content have been flushed on the wire before callback is called.

Adds a chunk of data to the request body. The first write operation may cause the request headers to be issued on the wire. After the first write operation, it is not allowed to add or remove a custom header.

request.end([chunk][, encoding][, callback])

• chunk (string | Buffer) (optional)
• encoding string (optional)
• callback Function (optional)

Returns this.

Sends the last chunk of the request data. Subsequent write or end operations will not be allowed. The finish event is emitted just after the end operation.

request.abort()

Cancels an ongoing HTTP transaction. If the request has already emitted the close event, the abort operation will have no effect. Otherwise an ongoing event will emit abort and close events. Additionally, if there is an ongoing response object,it will emit the aborted event.

request.followRedirect()

Continues any pending redirection. Can only be called during a 'redirect' event.

request.getUploadProgress()

Returns Object:

• active boolean - Whether the request is currently active. If this is false no other properties will be set
• started boolean - Whether the upload has started. If this is false both current and total will be set to 0.
• current Integer - The number of bytes that have been uploaded so far
• total Integer - The number of bytes that will be uploaded this request

You can use this method in conjunction with POST requests to get the progress of a file upload or other data transfer.