modernizr/src/testRunner.js

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

define(['tests', 'Modernizr', 'classes', 'is'], function(tests, Modernizr, classes, is) {
  /**
   * Run through all tests and detect their support in the current UA.
   *
   * @access private
   */

  function testRunner() {
    var featureNames;
    var feature;
    var aliasIdx;
    var result;
    var nameIdx;
    var featureName;
    var featureNameSplit;

    for (var featureIdx in tests) {
      if (tests.hasOwnProperty(featureIdx)) {
        featureNames = [];
        feature = tests[featureIdx];
        // run the test, throw the return value into the Modernizr,
        // then based on that boolean, define an appropriate className
        // and push it into an array of classes we'll join later.
        //
        // If there is no name, it's an 'async' test that is run,
        // but not directly added to the object. That should
        // be done with a post-run addTest call.
        if (feature.name) {
          featureNames.push(feature.name.toLowerCase());

          if (feature.options && feature.options.aliases && feature.options.aliases.length) {
            // Add all the aliases into the names list
            for (aliasIdx = 0; aliasIdx < feature.options.aliases.length; aliasIdx++) {
              featureNames.push(feature.options.aliases[aliasIdx].toLowerCase());
            }
          }
        }

        // Run the test, or use the raw value if it's not a function
        result = is(feature.fn, 'function') ? feature.fn() : feature.fn;


        // Set each of the names on the Modernizr object
        for (nameIdx = 0; nameIdx < featureNames.length; nameIdx++) {
          featureName = featureNames[nameIdx];
          // Support dot properties as sub tests. We don't do checking to make sure
          // that the implied parent tests have been added. You must call them in
          // order (either in the test, or make the parent test a dependency).
          //
          // Cap it to TWO to make the logic simple and because who needs that kind of subtesting
          // hashtag famous last words
          featureNameSplit = featureName.split('.');

          if (featureNameSplit.length === 1) {
            Modernizr[featureNameSplit[0]] = result;
          } else {
            // cast to a Boolean, if not one already
            if (Modernizr[featureNameSplit[0]] && !(Modernizr[featureNameSplit[0]] instanceof Boolean)) {
              Modernizr[featureNameSplit[0]] = new Boolean(Modernizr[featureNameSplit[0]]);
            }

            Modernizr[featureNameSplit[0]][featureNameSplit[1]] = result;
          }

          classes.push((result ? '' : 'no-') + featureNameSplit.join('-'));
        }
      }
    }
  }
  return testRunner;
});