node-webshot

Webshot provides a simple API for taking webpage screenshots. The module is a light wrapper around PhantomJS, which utilizes WebKit to perform the page rendering.

Examples

A simple url example:

var webshot = require('webshot');

webshot('google.com', 'google.png', function(err) {
  // screenshot now saved to google.png
});

An html example:

var webshot = require('webshot');

webshot('<html><body>Hello World</body></html>', 'hello_world.png', {siteType:'html'}, function(err) {
  // screenshot now saved to hello_world.png
});

Alternately, the screenshot can be streamed back to the caller:

var webshot = require('webshot');
var fs      = require('fs');

webshot('google.com', function(err, renderStream) {
  var file = fs.createWriteStream('google.png', {encoding: 'binary'});

  renderStream.on('data', function(data) {
    file.write(data.toString('binary'), 'binary');
  });
});

An example showing how to take a screenshot of a site's mobile version:

var webshot = require('webshot');

var options = {
  screenSize: {
    width: 320
  , height: 480
  }
, shotSize: {
    width: 320
  , height: 'all'
  }
, userAgent: 'Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_2 like Mac OS X; en-us)'
    + ' AppleWebKit/531.21.20 (KHTML, like Gecko) Mobile/7B298g'
}

webshot('flickr.com', 'flickr.jpeg', options, function(err) {
  // screenshot now saved to flickr.jpeg
});

Options

An optional options object can be passed as the parameter directly preceding the callback in a call to webshot.

Option	Default Value	Description
windowSize	{ width: 1024 , height: 768 }	The dimensions of the browser window. screenSize is an alias for this property.
shotSize	{ width: 'window' , height: 'window' }	The area of the page document, starting at the upper left corner, to render. Possible values are 'screen', 'all', and a number defining a pixel length. 'window' causes the length to be set to the length of the window (i.e. the shot displays what is initially visible within the browser window). 'all' causes the length to be set to the length of the document along the given dimension.
shotOffset	{ left: 0 , right: 0 , top: 0 , bottom: 0 }	The left and top offsets define the upper left corner of the screenshot rectangle. The right and bottom offsets allow pixels to be removed from the shotSize dimensions (e.g. a shotSize height of 'all' with a bottom offset of 30 would cause all but the last 30 rows of pixels on the site to be rendered).
phantomPath	'phantomjs'	The location of phantomjs. Webshot tries to use the binary provided by the phantomjs NPM module, and falls back to 'phantomjs' if the module isn't available.
phantomConfig	{}	Object with key value pairs corresponding to phantomjs command line options. Don't include `--`. For example: `phantomConfig: {'ignore-ssl-errors': 'true'}`
customHeaders	null	Any additional headers to be sent in the HTTP request.
defaultWhiteBackground	false	When taking the screenshot, adds a white background if not defined elsewhere.
customCSS	''	When taking the screenshot, adds custom CSS rules if defined.
quality	75	JPEG compression quality. A higher number will look better, but creates a larger file. Quality setting has no effect when streaming.
streamType	'png'	If streaming is used, this designates the file format of the streamed rendering. Possible values are 'png', 'jpg', and 'jpeg'.
siteType	'url'	siteType indicates whether the content needs to be requested ('url'), loaded locally ('file'), or is being provided directly as a string ('html').
renderDelay	0	Number of milliseconds to wait after a page loads before taking the screenshot.
timeout	0	Number of milliseconds to wait before killing the phantomjs process and assuming webshotting has failed. (0 is no timeout.)
takeShotOnCallback	false	Wait for the web page to signal to webshot when to take the photo using `window.callPhantom('takeShot');`
errorIfStatusIsNot200	false	If the loaded page has a non-200 status code, don't take a screenshot, cause an error instead.

Phantom page properties

In addition to these options, the following options can be specified and will be passed to the Phantom page object: paperSize, zoomFactor, cookies, customHeaders, and settings.

Phantom callbacks

Arbitrary scripts can be run on the page before it gets rendered by using any of Phantom's page callbacks, such as onLoadFinished or onResourceRequested. For example, the script below changes the text of every link on the page:

var options = {
  onLoadFinished: function() {
    var links = document.getElementsByTagName('a');

    for (var i=0; i<links.length; i++) {
      var link = links[i];
      link.innerHTML = 'My custom text';
    } 
  }
}

Note that the script will be serialized and then passed to Phantom as text, so all variable scope information will be lost. However, variables from the caller can be passed into the script as follows:

var options = {
  onLoadFinished: {
    fn: function() {
      var links = document.getElementsByTagName('a');

      for (var i=0; i<links.length; i++) {
        var link = links[i];
        link.innerHTML = this.foo;
      } 
    }
  , context: {foo: 'My custom text'}
  }
}

Tests

Tests are written with Mocha and can be run with npm test. The tests use node-imagemagick and thus require that the imagemagick CLI tools be installed.

Running on Heroku

See this comment.

Grunt

grunt-webshot is a Grunt wrapper for this package.

License

(The MIT License)

Copyright (c) 2012 Brenden Kokoszka

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the 'Software'), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

lebek/node-webshot