376 lines
12 KiB
Markdown
376 lines
12 KiB
Markdown
# protocol
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> Register a custom protocol and intercept existing protocol requests.
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Process: [Main](../glossary.md#main-process)
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An example of implementing a protocol that has the same effect as the
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`file://` protocol:
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```javascript
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const {app, protocol} = require('electron')
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const path = require('path')
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app.on('ready', () => {
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protocol.registerFileProtocol('atom', (request, callback) => {
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const url = request.url.substr(7)
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callback({path: path.normalize(`${__dirname}/${url}`)})
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}, (error) => {
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if (error) console.error('Failed to register protocol')
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})
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})
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```
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**Note:** All methods unless specified can only be used after the `ready` event
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of the `app` module gets emitted.
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## Methods
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The `protocol` module has the following methods:
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### `protocol.registerStandardSchemes(schemes[, options])`
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* `schemes` String[] - Custom schemes to be registered as standard schemes.
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* `options` Object (optional)
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* `secure` Boolean (optional) - `true` to register the scheme as secure.
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Default `false`.
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A standard scheme adheres to what RFC 3986 calls [generic URI
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syntax](https://tools.ietf.org/html/rfc3986#section-3). For example `http` and
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`https` are standard schemes, while `file` is not.
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Registering a scheme as standard, will allow relative and absolute resources to
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be resolved correctly when served. Otherwise the scheme will behave like the
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`file` protocol, but without the ability to resolve relative URLs.
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For example when you load following page with custom protocol without
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registering it as standard scheme, the image will not be loaded because
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non-standard schemes can not recognize relative URLs:
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```html
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<body>
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<img src='test.png'>
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</body>
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```
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Registering a scheme as standard will allow access to files through the
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[FileSystem API][file-system-api]. Otherwise the renderer will throw a security
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error for the scheme.
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By default web storage apis (localStorage, sessionStorage, webSQL, indexedDB, cookies)
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are disabled for non standard schemes. So in general if you want to register a
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custom protocol to replace the `http` protocol, you have to register it as a standard scheme:
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```javascript
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const {app, protocol} = require('electron')
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protocol.registerStandardSchemes(['atom'])
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app.on('ready', () => {
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protocol.registerHttpProtocol('atom', '...')
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})
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```
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**Note:** This method can only be used before the `ready` event of the `app`
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module gets emitted.
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### `protocol.registerServiceWorkerSchemes(schemes)`
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* `schemes` String[] - Custom schemes to be registered to handle service workers.
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### `protocol.registerFileProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `filePath` String (optional)
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* `completion` Function (optional)
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* `error` Error
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Registers a protocol of `scheme` that will send the file as a response. The
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`handler` will be called with `handler(request, callback)` when a `request` is
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going to be created with `scheme`. `completion` will be called with
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`completion(null)` when `scheme` is successfully registered or
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`completion(error)` when failed.
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To handle the `request`, the `callback` should be called with either the file's
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path or an object that has a `path` property, e.g. `callback(filePath)` or
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`callback({path: filePath})`.
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When `callback` is called with nothing, a number, or an object that has an
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`error` property, the `request` will fail with the `error` number you
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specified. For the available error numbers you can use, please see the
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[net error list][net-error].
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By default the `scheme` is treated like `http:`, which is parsed differently
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than protocols that follow the "generic URI syntax" like `file:`, so you
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probably want to call `protocol.registerStandardSchemes` to have your scheme
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treated as a standard scheme.
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### `protocol.registerBufferProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `buffer` (Buffer | [MimeTypedBuffer](structures/mime-typed-buffer.md)) (optional)
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* `completion` Function (optional)
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* `error` Error
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Registers a protocol of `scheme` that will send a `Buffer` as a response.
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The usage is the same with `registerFileProtocol`, except that the `callback`
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should be called with either a `Buffer` object or an object that has the `data`,
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`mimeType`, and `charset` properties.
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Example:
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```javascript
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const {protocol} = require('electron')
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protocol.registerBufferProtocol('atom', (request, callback) => {
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callback({mimeType: 'text/html', data: Buffer.from('<h5>Response</h5>')})
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}, (error) => {
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if (error) console.error('Failed to register protocol')
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})
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```
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### `protocol.registerStringProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `data` String (optional)
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* `completion` Function (optional)
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* `error` Error
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Registers a protocol of `scheme` that will send a `String` as a response.
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The usage is the same with `registerFileProtocol`, except that the `callback`
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should be called with either a `String` or an object that has the `data`,
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`mimeType`, and `charset` properties.
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### `protocol.registerHttpProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `redirectRequest` Object
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* `url` String
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* `method` String
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* `session` Object (optional)
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* `uploadData` Object (optional)
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* `contentType` String - MIME type of the content.
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* `data` String - Content to be sent.
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* `completion` Function (optional)
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* `error` Error
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Registers a protocol of `scheme` that will send an HTTP request as a response.
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The usage is the same with `registerFileProtocol`, except that the `callback`
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should be called with a `redirectRequest` object that has the `url`, `method`,
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`referrer`, `uploadData` and `session` properties.
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By default the HTTP request will reuse the current session. If you want the
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request to have a different session you should set `session` to `null`.
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For POST requests the `uploadData` object must be provided.
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### `protocol.registerStreamProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `headers` Object
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `stream` (ReadableStream | [StreamProtocolResponse](structures/stream-protocol-response.md)) (optional)
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* `completion` Function (optional)
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* `error` Error
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Registers a protocol of `scheme` that will send a `Readable` as a response.
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The usage is similar to the other `register{Any}Protocol`, except that the
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`callback` should be called with either a `Readable` object or an object that
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has the `data`, `statusCode`, and `headers` properties.
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Example:
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```javascript
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const {protocol} = require('electron')
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const {PassThrough} = require('stream')
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function createStream (text) {
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const rv = new PassThrough() // PassThrough is also a Readable stream
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rv.push(text)
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rv.push(null)
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return rv
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}
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protocol.registerStreamProtocol('atom', (request, callback) => {
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callback({
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statusCode: 200,
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headers: {
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'content-type': 'text/html'
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},
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data: createStream('<h5>Response</h5>')
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})
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}, (error) => {
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if (error) console.error('Failed to register protocol')
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})
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```
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It is possible to pass any object that implements the readable stream API (emits
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`data`/`end`/`error` events). For example, here's how a file could be returned:
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```javascript
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const {protocol} = require('electron')
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const fs = require('fs')
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protocol.registerStreamProtocol('atom', (request, callback) => {
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callback(fs.createReadStream('index.html'))
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}, (error) => {
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if (error) console.error('Failed to register protocol')
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})
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```
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### `protocol.unregisterProtocol(scheme[, completion])`
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* `scheme` String
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* `completion` Function (optional)
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* `error` Error
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Unregisters the custom protocol of `scheme`.
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### `protocol.isProtocolHandled(scheme, callback)`
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* `scheme` String
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* `callback` Function
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* `error` Error
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The `callback` will be called with a boolean that indicates whether there is
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already a handler for `scheme`.
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### `protocol.interceptFileProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `filePath` String
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* `completion` Function (optional)
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* `error` Error
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Intercepts `scheme` protocol and uses `handler` as the protocol's new handler
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which sends a file as a response.
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### `protocol.interceptStringProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `data` String (optional)
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* `completion` Function (optional)
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* `error` Error
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Intercepts `scheme` protocol and uses `handler` as the protocol's new handler
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which sends a `String` as a response.
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### `protocol.interceptBufferProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `buffer` Buffer (optional)
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* `completion` Function (optional)
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* `error` Error
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Intercepts `scheme` protocol and uses `handler` as the protocol's new handler
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which sends a `Buffer` as a response.
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### `protocol.interceptHttpProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `redirectRequest` Object
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* `url` String
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* `method` String
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* `session` Object (optional)
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* `uploadData` Object (optional)
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* `contentType` String - MIME type of the content.
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* `data` String - Content to be sent.
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* `completion` Function (optional)
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* `error` Error
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Intercepts `scheme` protocol and uses `handler` as the protocol's new handler
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which sends a new HTTP request as a response.
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### `protocol.interceptStreamProtocol(scheme, handler[, completion])`
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* `scheme` String
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* `handler` Function
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* `request` Object
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* `url` String
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* `headers` Object
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* `referrer` String
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* `method` String
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* `uploadData` [UploadData[]](structures/upload-data.md)
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* `callback` Function
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* `stream` (ReadableStream | [StreamProtocolResponse](structures/stream-protocol-response.md)) (optional)
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* `completion` Function (optional)
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* `error` Error
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Same as `protocol.registerStreamProtocol`, except that it replaces an existing
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protocol handler.
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### `protocol.uninterceptProtocol(scheme[, completion])`
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* `scheme` String
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* `completion` Function (optional)
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* `error` Error
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Remove the interceptor installed for `scheme` and restore its original handler.
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[net-error]: https://code.google.com/p/chromium/codesearch#chromium/src/net/base/net_error_list.h
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[file-system-api]: https://developer.mozilla.org/en-US/docs/Web/API/LocalFileSystem
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