modernizr/feature-detects/css/gradients.js

Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser.

/*!
{
  "name": "CSS Gradients",
  "caniuse": "css-gradients",
  "property": "cssgradients",
  "tags": ["css"],
  "notes": [{
    "name": "Webkit Gradient Syntax",
    "href": "http://webkit.org/blog/175/introducing-css-gradients/"
  },{
    "name": "Mozilla Linear Gradient Syntax",
    "href": "http://developer.mozilla.org/en/CSS/-moz-linear-gradient"
  },{
    "name": "Mozilla Radial Gradient Syntax",
    "href": "http://developer.mozilla.org/en/CSS/-moz-radial-gradient"
  },{
    "name": "W3C Gradient Spec",
    "href": "dev.w3.org/csswg/css3-images/#gradients-"
  }]
}
!*/
define(['Modernizr', 'prefixes', 'createElement'], function( Modernizr, prefixes, createElement ) {

  Modernizr.addTest('cssgradients', function() {

    var str1 = 'background-image:';
    var str2 = 'gradient(linear,left top,right bottom,from(#9f9),to(white));';
    var str3 = 'linear-gradient(left top,#9f9, white);';

    var css =
      // legacy webkit syntax (FIXME: remove when syntax not in use anymore)
      (str1 + '-webkit- '.split(' ').join(str2 + str1) +
       // standard syntax             // trailing 'background-image:'
       prefixes.join(str3 + str1)).slice(0, -str1.length);

    var elem = createElement('div');
    var style = elem.style;
    style.cssText = css;

    // IE6 returns undefined so cast to string
    return ('' + style.backgroundImage).indexOf('gradient') > -1;
  });
});