Bfn-webshot NPM

bfn-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');

var renderStream = webshot('google.com');
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.

PhantomJS version

By default this package installs PhantomJS 1.9.x. Several issues exist in this version that are fixed in v2, but v2 is not yet stable across all platforms. The phantomPath option can be used to get around this if you want to try a more recent PhantomJS version. See this issue: https://github.com/brenden/node-webshot/issues/100

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.