File: yui/js/features.js

            var feature_tests = {};
            
            /**
            Contains the core of YUI's feature test architecture.
            @module features
            */
            
            /**
            * Feature detection
            * @class Features
            * @static
            */
            
            Y.mix(Y.namespace('Features'), {
            
                /**
                * Object hash of all registered feature tests
                * @property tests
                * @type Object
                */
                tests: feature_tests,
            
                /**
                * Add a test to the system
                *
                *   ```
                *   Y.Features.add("load", "1", {});
                *   ```
                *
                * @method add
                * @param {String} cat The category, right now only 'load' is supported
                * @param {String} name The number sequence of the test, how it's reported in the URL or config: 1, 2, 3
                * @param {Object} o Object containing test properties
                * @param {String} o.name The name of the test
                * @param {Function} o.test The test function to execute, the only argument to the function is the `Y` instance
                * @param {String} o.trigger The module that triggers this test.
                */
                add: function(cat, name, o) {
                    feature_tests[cat] = feature_tests[cat] || {};
                    feature_tests[cat][name] = o;
                },
                /**
                * Execute all tests of a given category and return the serialized results
                *
                *   ```
                *   caps=1:1;2:1;3:0
                *   ```
                * @method all
                * @param {String} cat The category to execute
                * @param {Array} args The arguments to pass to the test function
                * @return {String} A semi-colon separated string of tests and their success/failure: 1:1;2:1;3:0
                */
                all: function(cat, args) {
                    var cat_o = feature_tests[cat],
                        // results = {};
                        result = [];
                    if (cat_o) {
                        Y.Object.each(cat_o, function(v, k) {
                            result.push(k + ':' + (Y.Features.test(cat, k, args) ? 1 : 0));
                        });
                    }
            
                    return (result.length) ? result.join(';') : '';
                },
                /**
                * Run a specific test and return a Boolean response.
                *
                *   ```
                *   Y.Features.test("load", "1");
                *   ```
                *
                * @method test
                * @param {String} cat The category of the test to run
                * @param {String} name The name of the test to run
                * @param {Array} args The arguments to pass to the test function
                * @return {Boolean} True or false if the test passed/failed.
                */
                test: function(cat, name, args) {
                    args = args || [];
                    var result, ua, test,
                        cat_o = feature_tests[cat],
                        feature = cat_o && cat_o[name];
            
                    if (!feature) {
                        Y.log('Feature test ' + cat + ', ' + name + ' not found');
                    } else {
            
                        result = feature.result;
            
                        if (Y.Lang.isUndefined(result)) {
            
                            ua = feature.ua;
                            if (ua) {
                                result = (Y.UA[ua]);
                            }
            
                            test = feature.test;
                            if (test && ((!ua) || result)) {
                                result = test.apply(Y, args);
                            }
            
                            feature.result = result;
                        }
                    }
            
                    return result;
                }
            });
            
            // Y.Features.add("load", "1", {});
            // Y.Features.test("load", "1");
            // caps=1:1;2:0;3:1;