Browser manages a browser instance, creating it with a predefined
settings, opening and closing pages. Instantiating Browser class does
not necessarily result in launching browser; the instance will be launched when the need will arise.
#### new Browser([options])
-`options` [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) Set of configurable options to set on the browser. Can have the following fields:
-`headless` [<boolean>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type) Wether to run chromium in headless mode. Defaults to `true`.
-`remoteDebuggingPort` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) Specify a remote debugging port to open on chromium instance. Defaults to `9229`.
-`executablePath` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Path to a chromium executable to run instead of bundled chromium.
-`args` [<Array>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array) Additional arguments to pass to the chromium instance. List of chromium flags could be found [here](http://peter.sh/experiments/chromium-command-line-switches/).
Closes chromium application with all the pages (if any were opened). The browser object itself is considered to be disposed and could not be used anymore.
### class: Page
Page provides interface to interact with a tab in a browser. Pages are created by browser:
```javascript
var browser = new Browser();
browser.newPage().then(page => {
...
});
```
Pages could be closed by `page.close()` method.
#### page.addScriptTag(url)
-`url` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Url of a script to be added
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves as the script gets added and loads.
#### page.injectFile(filePath)
-`url` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Path to the javascript file to be injected into page.
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when file gets successfully evaluated in page.
#### page.setInPageCallback(name, callback)
-`url` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Name of the callback to be assigned on window object
-`callback` [<Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) Callback function which will be called in node.js
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when callback is successfully initialized
#### page.setExtraHTTPHeaders(headers)
-`headers` [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) Key-value set of additional http headers to be sent with every request.
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when additional headers are installed
#### page.extraHTTPHeaders()
- returns: [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) Key-value set of additional http headers, which will be sent with every request.
#### page.setUserAgentOverride(userAgent)
-`userAgent` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Specific user agent to use in this page
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when the user agent is set.
#### page.userAgentOverride()
- returns: [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Returns user agent override, if any.
- returns: [<Promise<string>>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Promise which resolves with the current page url.
#### page.setContent(html)
-`html` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) HTML markup to assign to the page.
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when the content is successfully assigned.
#### page.navigate(url)
-`url` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) URL to navigate page to
- returns: [<Promise<boolean>>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type) Promise which resolves when the page is navigated. The promise resolves to:
-`true` if the navigation succeeds and page's `load` event is fired.
-`false` if the navigation fails due to bad URL or SSL errors.
-`size` [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) An object with two fields:
-`width` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) Specify page's width in pixels.
-`height` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) Specify page's height in pixels.
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when the dimensions are updated.
- returns: [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) An object with two fields:
-`width` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) Page's width in pixels.
-`height` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) Page's height in pixels.
#### page.evaluate(fun, args)
-`fun` [<Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) Function to be evaluated in browser context
-`args` [<Array>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array) Arguments to pass to `fun`
- returns: [<Promise<Object>>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves to function return value
#### page.evaluateOnInitialized(fun, args)
-`fun` [<Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) Function to be evaluated in browser context
-`args` [<Array>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array) Arguments to pass to `fun`
- returns: [<Promise<Object>>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves to function
#### page.screenshot(type[, clipRect])
-`type` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) Specify screenshot type, could be either `jpeg` or `png`.
-`clipRect` [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) An object which specifies clipping region of the page. Should have the following fields:
-`x` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) x-coordinate of top-left corner of clip area
-`y` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) y-coordinate of top-left corner of clip area
-`width` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) width of clipping area
-`height` [<number>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type) height of clipping area
- returns: [<Promise<Buffer>>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves to buffer with captured screenshot
#### page.printToPDF(filePath[, options])
-`filePath` [<string>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type) The file path to save image to. The screenshot type will be inferred from file extension
-`options` [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) Options object which might have the following properties:
- returns: [<Promise>](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) Promise which resolves when the PDF is saved.
