Register a custom protocol and intercept existing protocol requests.
Process: Main
An example of implementing a protocol that has the same effect as the
file://
protocol:
const {app, protocol} = require('electron')
const path = require('path')
app.on('ready', () => {
protocol.registerFileProtocol('atom', (request, callback) => {
const url = request.url.substr(7)
callback({path: path.normalize(`${__dirname}/${url}`)})
}, (error) => {
if (error) console.error('Failed to register protocol')
})
})
Note: All methods unless specified can only be used after the ready
event
of the app
module gets emitted.
The protocol
module has the following methods:
protocol.registerStandardSchemes(schemes[, options])
schemes
String[] - Custom schemes to be registered as standard schemes.options
Object (optional)
secure
Boolean (optional) - true
to register the scheme as secure.
Default false
.A standard scheme adheres to what RFC 3986 calls generic URI
syntax. For example http
and
https
are standard schemes, while file
is not.
Registering a scheme as standard, will allow relative and absolute resources to
be resolved correctly when served. Otherwise the scheme will behave like the
file
protocol, but without the ability to resolve relative URLs.
For example when you load following page with custom protocol without registering it as standard scheme, the image will not be loaded because non-standard schemes can not recognize relative URLs:
<body>
<img src='test.png'>
</body>
Registering a scheme as standard will allow access to files through the FileSystem API. Otherwise the renderer will throw a security error for the scheme.
By default web storage apis (localStorage, sessionStorage, webSQL, indexedDB, cookies)
are disabled for non standard schemes. So in general if you want to register a
custom protocol to replace the http
protocol, you have to register it as a standard scheme:
const {app, protocol} = require('electron')
protocol.registerStandardSchemes(['atom'])
app.on('ready', () => {
protocol.registerHttpProtocol('atom', '...')
})
Note: This method can only be used before the ready
event of the app
module gets emitted.
protocol.registerServiceWorkerSchemes(schemes)
schemes
String[] - Custom schemes to be registered to handle service workers.protocol.registerFileProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
FunctionfilePath
String (optional)completion
Function (optional)
error
ErrorRegisters a protocol of scheme
that will send the file as a response. The
handler
will be called with handler(request, callback)
when a request
is
going to be created with scheme
. completion
will be called with
completion(null)
when scheme
is successfully registered or
completion(error)
when failed.
To handle the request
, the callback
should be called with either the file's
path or an object that has a path
property, e.g. callback(filePath)
or
callback({path: filePath})
.
When callback
is called with nothing, a number, or an object that has an
error
property, the request
will fail with the error
number you
specified. For the available error numbers you can use, please see the
net error list.
By default the scheme
is treated like http:
, which is parsed differently
than protocols that follow the "generic URI syntax" like file:
, so you
probably want to call protocol.registerStandardSchemes
to have your scheme
treated as a standard scheme.
protocol.registerBufferProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
Functionbuffer
(Buffer | MimeTypedBuffer) (optional)completion
Function (optional)
error
ErrorRegisters a protocol of scheme
that will send a Buffer
as a response.
The usage is the same with registerFileProtocol
, except that the callback
should be called with either a Buffer
object or an object that has the data
,
mimeType
, and charset
properties.
Example:
const {protocol} = require('electron')
protocol.registerBufferProtocol('atom', (request, callback) => {
callback({mimeType: 'text/html', data: Buffer.from('<h5>Response</h5>')})
}, (error) => {
if (error) console.error('Failed to register protocol')
})
protocol.registerStringProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
Functiondata
String (optional)completion
Function (optional)
error
ErrorRegisters a protocol of scheme
that will send a String
as a response.
The usage is the same with registerFileProtocol
, except that the callback
should be called with either a String
or an object that has the data
,
mimeType
, and charset
properties.
protocol.registerHttpProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
FunctionredirectRequest
Object
url
Stringmethod
Stringsession
Object (optional)uploadData
Object (optional)contentType
String - MIME type of the content.data
String - Content to be sent.completion
Function (optional)
error
ErrorRegisters a protocol of scheme
that will send an HTTP request as a response.
The usage is the same with registerFileProtocol
, except that the callback
should be called with a redirectRequest
object that has the url
, method
,
referrer
, uploadData
and session
properties.
By default the HTTP request will reuse the current session. If you want the
request to have a different session you should set session
to null
.
For POST requests the uploadData
object must be provided.
protocol.registerStreamProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringheaders
Objectreferrer
Stringmethod
StringuploadData
UploadData[]callback
Functionstream
(ReadableStream | StreamProtocolResponse) (optional)completion
Function (optional)
error
ErrorRegisters a protocol of scheme
that will send a Readable
as a response.
The usage is similar to the other register{Any}Protocol
, except that the
callback
should be called with either a Readable
object or an object that
has the data
, statusCode
, and headers
properties.
Example:
const {protocol} = require('electron')
const {PassThrough} = require('stream')
function createStream (text) {
const rv = new PassThrough() // PassThrough is also a Readable stream
rv.push(text)
rv.push(null)
return rv
}
protocol.registerStreamProtocol('atom', (request, callback) => {
callback({
statusCode: 200,
headers: {
'content-type': 'text/html'
},
data: createStream('<h5>Response</h5>')
})
}, (error) => {
if (error) console.error('Failed to register protocol')
})
It is possible to pass any object that implements the readable stream API (emits
data
/end
/error
events). For example, here's how a file could be returned:
const {protocol} = require('electron')
const fs = require('fs')
protocol.registerStreamProtocol('atom', (request, callback) => {
callback(fs.createReadStream('index.html'))
}, (error) => {
if (error) console.error('Failed to register protocol')
})
protocol.unregisterProtocol(scheme[, completion])
scheme
Stringcompletion
Function (optional)
error
ErrorUnregisters the custom protocol of scheme
.
protocol.isProtocolHandled(scheme, callback)
scheme
Stringcallback
Function
error
ErrorThe callback
will be called with a boolean that indicates whether there is
already a handler for scheme
.
protocol.interceptFileProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
FunctionfilePath
Stringcompletion
Function (optional)
error
ErrorIntercepts scheme
protocol and uses handler
as the protocol's new handler
which sends a file as a response.
protocol.interceptStringProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
Functiondata
String (optional)completion
Function (optional)
error
ErrorIntercepts scheme
protocol and uses handler
as the protocol's new handler
which sends a String
as a response.
protocol.interceptBufferProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
Functionbuffer
Buffer (optional)completion
Function (optional)
error
ErrorIntercepts scheme
protocol and uses handler
as the protocol's new handler
which sends a Buffer
as a response.
protocol.interceptHttpProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringreferrer
Stringmethod
StringuploadData
UploadData[]callback
FunctionredirectRequest
Object
url
Stringmethod
Stringsession
Object (optional)uploadData
Object (optional)contentType
String - MIME type of the content.data
String - Content to be sent.completion
Function (optional)
error
ErrorIntercepts scheme
protocol and uses handler
as the protocol's new handler
which sends a new HTTP request as a response.
protocol.interceptStreamProtocol(scheme, handler[, completion])
scheme
Stringhandler
Function
request
Objecturl
Stringheaders
Objectreferrer
Stringmethod
StringuploadData
UploadData[]callback
Functionstream
(ReadableStream | StreamProtocolResponse) (optional)completion
Function (optional)
error
ErrorSame as protocol.registerStreamProtocol
, except that it replaces an existing
protocol handler.
protocol.uninterceptProtocol(scheme[, completion])
scheme
Stringcompletion
Function (optional)
error
ErrorRemove the interceptor installed for scheme
and restore its original handler.