468 lines
10 KiB
Markdown
468 lines
10 KiB
Markdown
# webContents
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`webContents` is an
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[EventEmitter](http://nodejs.org/api/events.html#events_class_events_eventemitter).
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It is responsible for rendering and controlling a web page and is a property of the [`BrowserWindow`](browser-window.md) object. An example of accessing the `webContents` object:
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```javascript
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var BrowserWindow = require('browser-window');
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var win = new BroswerWindow({width: 800, height: 1500});
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win.loadUrl("http://github.com");
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var webContents = win.webContents
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```
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## Events
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The `webContents` object emits the following events:
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### Event: 'did-finish-load'
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Emitted when the navigation is done, i.e. the spinner of the tab has stopped
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spinning, and the `onload` event was dispatched.
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### Event: 'did-fail-load'
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Returns:
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* `event` Event
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* `errorCode` Integer
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* `errorDescription` String
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This event is like `did-finish-load` but emitted when the load failed or was
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cancelled, e.g. `window.stop()` is invoked.
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### Event: 'did-frame-finish-load'
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Returns:
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* `event` Event
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* `isMainFrame` Boolean
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Emitted when a frame has done navigation.
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### Event: 'did-start-loading'
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Corresponds to the points in time when the spinner of the tab started spinning.
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### Event: 'did-stop-loading'
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Corresponds to the points in time when the spinner of the tab stopped spinning.
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### Event: 'did-get-response-details'
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Returns:
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* `event` Event
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* `status` Boolean
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* `newUrl` String
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* `originalUrl` String
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* `httpResponseCode` Integer
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* `requestMethod` String
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* `referrer` String
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* `headers` Object
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Emitted when details regarding a requested resource is available.
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`status` indicates the socket connection to download the resource.
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### Event: 'did-get-redirect-request'
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Returns:
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* `event` Event
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* `oldUrl` String
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* `newUrl` String
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* `isMainFrame` Boolean
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Emitted when a redirect was received while requesting a resource.
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### Event: 'dom-ready'
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Returns:
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* `event` Event
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Emitted when the document in the given frame is loaded.
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### Event: 'page-favicon-updated'
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Returns:
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* `event` Event
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* `favicons` Array - Array of Urls
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Emitted when page receives favicon urls.
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### Event: 'new-window'
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Returns:
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* `event` Event
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* `url` String
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* `frameName` String
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* `disposition` String - Can be `default`, `foreground-tab`, `background-tab`,
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`new-window` and `other`
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Emitted when the page requests to open a new window for a `url`. It could be
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requested by `window.open` or an external link like `<a target='_blank'>`.
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By default a new `BrowserWindow` will be created for the `url`.
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Calling `event.preventDefault()` can prevent creating new windows.
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### Event: 'will-navigate'
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Returns:
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* `event` Event
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* `url` String
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Emitted when user or the page wants to start a navigation, it can happen when
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`window.location` object is changed or user clicks a link in the page.
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This event will not emit when the navigation is started programmatically with APIs
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like `webContents.loadUrl` and `webContents.back`.
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Calling `event.preventDefault()` can prevent the navigation.
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### Event: 'crashed'
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Emitted when the renderer process has crashed.
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### Event: 'plugin-crashed'
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Returns:
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* `event` Event
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* `name` String
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* `version` String
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Emitted when a plugin process has crashed.
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### Event: 'destroyed'
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Emitted when `webContents` is destroyed.
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## Instance Methods
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The `webContents` object has the following instance methods:
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### `webContents.session`
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Returns the `Session` object used by this webContents.
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See [session documentation](session.md) for this object's methods.
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### `webContents.loadUrl(url[, options])`
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* `url` URL
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* `options` Object, properties:
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* `httpReferrer` String - A HTTP Referrer url
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* `userAgent` String - A user agent originating the request
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Loads the `url` in the window, the `url` must contains the protocol prefix,
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e.g. the `http://` or `file://`.
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### `webContents.getUrl()`
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```javascript
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var BrowserWindow = require('browser-window');
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var win = new BrowserWindow({width: 800, height: 600});
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win.loadUrl("http://github.com");
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var currentUrl = win.webContents.getUrl();
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```
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Returns URL of current web page.
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### `webContents.getTitle()`
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Returns the title of web page.
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### `webContents.isLoading()`
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Returns whether web page is still loading resources.
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### `webContents.isWaitingForResponse()`
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Returns whether web page is waiting for a first-response for the main resource
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of the page.
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### `webContents.stop()`
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Stops any pending navigation.
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### `webContents.reload()`
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Reloads current page.
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### `webContents.reloadIgnoringCache()`
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Reloads current page and ignores cache.
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### `webContents.canGoBack()`
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Returns whether the web page can go back.
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### `webContents.canGoForward()`
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Returns whether the web page can go forward.
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### `webContents.canGoToOffset(offset)`
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* `offset` Integer
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Returns whether the web page can go to `offset`.
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### `webContents.clearHistory()`
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Clears the navigation history.
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### `webContents.goBack()`
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Makes the web page go back.
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### `webContents.goForward()`
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Makes the web page go forward.
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### `webContents.goToIndex(index)`
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* `index` Integer
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Navigates to the specified absolute index.
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### `webContents.goToOffset(offset)`
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* `offset` Integer
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Navigates to the specified offset from the "current entry".
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### `webContents.isCrashed()`
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Whether the renderer process has crashed.
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### `webContents.setUserAgent(userAgent)`
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* `userAgent` String
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Overrides the user agent for this page.
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### `webContents.getUserAgent()`
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Returns a `String` represents the user agent for this page.
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### `webContents.insertCSS(css)`
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* `css` String
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Injects CSS into this page.
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### `webContents.executeJavaScript(code[, userGesture])`
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* `code` String
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* `userGesture` Boolean
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Evaluates `code` in page.
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In browser some HTML APIs like `requestFullScreen` can only be invoked if it
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is started by user gesture, by specifying `userGesture` to `true` developers
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can ignore this limitation.
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### `webContents.setAudioMuted(muted)`
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+ `muted` Boolean
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Set the page muted.
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### `webContents.isAudioMuted()`
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Returns whether this page has been muted.
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### `webContents.undo()`
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Executes editing command `undo` in page.
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### `webContents.redo()`
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Executes editing command `redo` in page.
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### `webContents.cut()`
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Executes editing command `cut` in page.
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### `webContents.copy()`
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Executes editing command `copy` in page.
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### `webContents.paste()`
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Executes editing command `paste` in page.
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### `webContents.pasteAndMatchStyle()`
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Executes editing command `pasteAndMatchStyle` in page.
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### `webContents.delete()`
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Executes editing command `delete` in page.
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### `webContents.selectAll()`
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Executes editing command `selectAll` in page.
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### `webContents.unselect()`
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Executes editing command `unselect` in page.
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### `webContents.replace(text)`
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* `text` String
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Executes editing command `replace` in page.
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### `webContents.replaceMisspelling(text)`
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* `text` String
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Executes editing command `replaceMisspelling` in page.
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### `webContents.hasServiceWorker(callback)`
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* `callback` Function
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Checks if any serviceworker is registered and returns boolean as
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response to `callback`.
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### `webContents.unregisterServiceWorker(callback)`
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* `callback` Function
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Unregisters any serviceworker if present and returns boolean as
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response to `callback` when the JS promise is fullfilled or false
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when the JS promise is rejected.
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### `webContents.print([options])`
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`options` Object, properties:
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* `silent` Boolean - Don't ask user for print settings, defaults to `false`
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* `printBackground` Boolean - Also prints the background color and image of
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the web page, defaults to `false`.
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Prints window's web page. When `silent` is set to `false`, Electron will pick
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up system's default printer and default settings for printing.
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Calling `window.print()` in web page is equivalent to call
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`webContents.print({silent: false, printBackground: false})`.
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**Note:** On Windows, the print API relies on `pdf.dll`. If your application
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doesn't need print feature, you can safely remove `pdf.dll` in saving binary
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size.
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### `webContents.printToPDF(options, callback)`
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`options` Object, properties:
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* `marginsType` Integer - Specify the type of margins to use
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* 0 - default
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* 1 - none
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* 2 - minimum
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* `pageSize` String - Specify page size of the generated PDF
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* `A4`
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* `A3`
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* `Legal`
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* `Letter`
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* `Tabloid`
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* `printBackground` Boolean - Whether to print CSS backgrounds.
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* `printSelectionOnly` Boolean - Whether to print selection only.
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* `landscape` Boolean - `true` for landscape, `false` for portrait.
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`callback` Function - `function(error, data) {}`
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* `error` Error
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* `data` Buffer - PDF file content
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Prints window's web page as PDF with Chromium's preview printing custom
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settings.
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By default, an empty `options` will be regarded as
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`{marginsType:0, printBackgrounds:false, printSelectionOnly:false,
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landscape:false}`.
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```javascript
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var BrowserWindow = require('browser-window');
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var fs = require('fs');
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var win = new BrowserWindow({width: 800, height: 600});
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win.loadUrl("http://github.com");
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win.webContents.on("did-finish-load", function() {
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// Use default printing options
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win.webContents.printToPDF({}, function(error, data) {
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if (error) throw error;
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fs.writeFile("/tmp/print.pdf", data, function(error) {
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if (err)
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throw error;
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console.log("Write PDF successfully.");
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})
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})
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});
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```
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### `webContents.addWorkSpace(path)`
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* `path` String
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Adds the specified path to devtools workspace.
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### `webContents.removeWorkSpace(path)`
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* `path` String
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Removes the specified path from devtools workspace.
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### `webContents.send(channel[, args...])`
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* `channel` String
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Send `args..` to the web page via `channel` in an asynchronous message, the web
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page can handle it by listening to the `channel` event of the `ipc` module.
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An example of sending messages from the main process to the renderer process:
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```javascript
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// On the main process.
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var window = null;
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app.on('ready', function() {
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window = new BrowserWindow({width: 800, height: 600});
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window.loadUrl('file://' + __dirname + '/index.html');
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window.webContents.on('did-finish-load', function() {
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window.webContents.send('ping', 'whoooooooh!');
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});
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});
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```
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```html
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<!-- index.html -->
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<html>
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<body>
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<script>
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require('ipc').on('ping', function(message) {
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console.log(message); // Prints "whoooooooh!"
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});
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</script>
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</body>
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</html>
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```
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**Note:**
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1. The IPC message handler in web pages does not have an `event` parameter, which
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is different from the handlers on the main process.
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2. There is no way to send synchronous messages from the main process to a
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renderer process, because it would be very easy to cause dead locks.
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