modernizr/src/testDOMProps.js

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

define(['is', 'fnBind'], function(is, fnBind) {
  /**
   * testDOMProps is a generic DOM property test; if a browser supports
   *   a certain property, it won't return undefined for it.
   *
   * @access private
   * @function testDOMProps
   * @param {Array<string>} props - An array of properties to test for
   * @param {object} obj - An object or Element you want to use to test the parameters again
   * @param {boolean|object} elem - An Element to bind the property lookup again. Use `false` to prevent the check
   * @returns {boolean|*} returns `false` if the prop is unsupported, otherwise the value that is supported
   */
  function testDOMProps(props, obj, elem) {
    var item;

    for (var i in props) {
      if (props[i] in obj) {

        // return the property name as a string
        if (elem === false) {
          return props[i];
        }

        item = obj[props[i]];

        // let's bind a function
        if (is(item, 'function')) {
          // bind to obj unless overridden
          return fnBind(item, elem || obj);
        }

        // return the unbound function or obj or value
        return item;
      }
    }
    return false;
  }

  return testDOMProps;
});