modernizr/src/computedStyle.js

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

define(function() {

  /**
   * wrapper around getComputedStyle, to fix issues with Firefox returning null when
   * called inside of a hidden iframe
   *
   * @access private
   * @function computedStyle
   * @param {HTMLElement|SVGElement} - The element we want to find the computed styles of
   * @param {string|null} [pseudoSelector]- An optional pseudo element selector (e.g. :before), of null if none
   * @returns {CSSStyleDeclaration}
   */

  function computedStyle(elem, pseudo, prop) {
    var result;

    if ('getComputedStyle' in window) {
      result = getComputedStyle.call(window, elem, pseudo);
      var console = window.console;

      if (result !== null) {
        if (prop) {
          result = result.getPropertyValue(prop);
        }
      } else {
        if (console) {
          var method = console.error ? 'error' : 'log';
          console[method].call(console, 'getComputedStyle returning null, its possible modernizr test results are inaccurate');
        }
      }
    } else {
      result = !pseudo && elem.currentStyle && elem.currentStyle[prop];
    }

    return result;
  }

  return computedStyle;
});