AngularJS 谁能讲解一下 Angular 的内部实现?

1272729223 · 2015年09月22日 · 最后由 1272729223 回复于 2015年09月22日 · 5169 次阅读

实在不想用angular了,只是想尽快弄明白它的内部实现,然后赶紧找个机会抛弃它

比如从angular启动一个应用之后,背后做了什么工作? 只要大致的流程即可,但是官方的文档看的头晕,以前以膜拜的态度来看待来自google的程序员,但是现在也开始怀疑有些无非也就是些瞎折腾完的小青年。

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这些是我剥离出来的核心的几百行代码。

(function(window, document, undefined) {

var
    jqLite,           // delay binding since jQuery could be loaded after us.
    jQuery,           // delay binding

    /** @name angular */
    angular           = window.angular || (window.angular = {}),
    angularModule,
    uid               = 0;

function noop() {}
noop.$inject = [];

function identity($) {return $;}
identity.$inject = [];

var jq = function() {
  if (isDefined(jq.name_)) return jq.name_;
  var el;
  var i, ii = ngAttrPrefixes.length, prefix, name;
  for (i = 0; i < ii; ++i) {
    prefix = ngAttrPrefixes[i];
    if (el = document.querySelector('[' + prefix.replace(':', '\\:') + 'jq]')) {
      name = el.getAttribute(prefix + 'jq');
      break;
    }
  }

  return (jq.name_ = name);
};

var ngAttrPrefixes = ['ng-', 'data-ng-', 'ng:', 'x-ng-'];

function getNgAttribute(element, ngAttr) {
  var attr, i, ii = ngAttrPrefixes.length;
  for (i = 0; i < ii; ++i) {
    attr = ngAttrPrefixes[i] + ngAttr;
    if (isString(attr = element.getAttribute(attr))) {
      return attr;
    }
  }
  return null;
}

function angularInit(element, bootstrap) {
  var appElement,
      module,
      config = {};

  // The element `element` has priority over any other element
  forEach(ngAttrPrefixes, function(prefix) {
    var name = prefix + 'app';

    if (!appElement && element.hasAttribute && element.hasAttribute(name)) {
      appElement = element;
      module = element.getAttribute(name);
    }
  });
  forEach(ngAttrPrefixes, function(prefix) {
    var name = prefix + 'app';
    var candidate;

    if (!appElement && (candidate = element.querySelector('[' + name.replace(':', '\\:') + ']'))) {
      appElement = candidate;
      module = candidate.getAttribute(name);
    }
  });
  if (appElement) {
    config.strictDi = getNgAttribute(appElement, "strict-di") !== null;
    bootstrap(appElement, module ? [module] : [], config);
  }
}

function bootstrap(element, modules, config) {
  if (!isObject(config)) config = {};
  var defaultConfig = {
    strictDi: false
  };
  config = extend(defaultConfig, config);
  var doBootstrap = function() {
    element = jqLite(element);

    if (element.injector()) {
      var tag = (element[0] === document) ? 'document' : startingTag(element);
      //Encode angle brackets to prevent input from being sanitized to empty string #8683
      throw ngMinErr(
          'btstrpd',
          "App Already Bootstrapped with this Element '{0}'",
          tag.replace(/</,'&lt;').replace(/>/,'&gt;'));
    }

    modules = modules || [];
    modules.unshift(['$provide', function($provide) {
      $provide.value('$rootElement', element);
    }]);

    if (config.debugInfoEnabled) {
      // Pushing so that this overrides `debugInfoEnabled` setting defined in user's `modules`.
      modules.push(['$compileProvider', function($compileProvider) {
        $compileProvider.debugInfoEnabled(true);
      }]);
    }

    modules.unshift('ng');
    var injector = createInjector(modules, config.strictDi);
    injector.invoke(['$rootScope', '$rootElement', '$compile', '$injector',
       function bootstrapApply(scope, element, compile, injector) {
        scope.$apply(function() {
          element.data('$injector', injector);
          compile(element)(scope);
        });
      }]
    );
    return injector;
  };

  var NG_ENABLE_DEBUG_INFO = /^NG_ENABLE_DEBUG_INFO!/;
  var NG_DEFER_BOOTSTRAP = /^NG_DEFER_BOOTSTRAP!/;

  if (window && NG_ENABLE_DEBUG_INFO.test(window.name)) {
    config.debugInfoEnabled = true;
    window.name = window.name.replace(NG_ENABLE_DEBUG_INFO, '');
  }

  if (window && !NG_DEFER_BOOTSTRAP.test(window.name)) {
    return doBootstrap();
  }

  window.name = window.name.replace(NG_DEFER_BOOTSTRAP, '');
  angular.resumeBootstrap = function(extraModules) {
    forEach(extraModules, function(module) {
      modules.push(module);
    });
    return doBootstrap();
  };

  if (isFunction(angular.resumeDeferredBootstrap)) {
    angular.resumeDeferredBootstrap();
  }
}

function bindJQuery() {
  var originalCleanData;

  if (bindJQueryFired) {
    return;
  }

  // bind to jQuery if present;
  var jqName = jq();
  jQuery = window.jQuery; // use default jQuery.
  if (isDefined(jqName)) { // `ngJq` present
    jQuery = jqName === null ? undefined : window[jqName]; // if empty; use jqLite. if not empty, use jQuery specified by `ngJq`.
  }

  // Use jQuery if it exists with proper functionality, otherwise default to us.
  // Angular 1.2+ requires jQuery 1.7+ for on()/off() support.
  // Angular 1.3+ technically requires at least jQuery 2.1+ but it may work with older
  // versions. It will not work for sure with jQuery <1.7, though.
  if (jQuery && jQuery.fn.on) {
    jqLite = jQuery;
    extend(jQuery.fn, {
      scope: JQLitePrototype.scope,
      isolateScope: JQLitePrototype.isolateScope,
      controller: JQLitePrototype.controller,
      injector: JQLitePrototype.injector,
      inheritedData: JQLitePrototype.inheritedData
    });

    // All nodes removed from the DOM via various jQuery APIs like .remove()
    // are passed through jQuery.cleanData. Monkey-patch this method to fire
    // the $destroy event on all removed nodes.
    originalCleanData = jQuery.cleanData;
    jQuery.cleanData = function(elems) {
      var events;
      if (!skipDestroyOnNextJQueryCleanData) {
        for (var i = 0, elem; (elem = elems[i]) != null; i++) {
          events = jQuery._data(elem, "events");
          if (events && events.$destroy) {
            jQuery(elem).triggerHandler('$destroy');
          }
        }
      } else {
        skipDestroyOnNextJQueryCleanData = false;
      }
      originalCleanData(elems);
    };
  } else {
    jqLite = JQLite;
  }

  angular.element = jqLite;

  // Prevent double-proxying.
  bindJQueryFired = true;
}

function setupModuleLoader(window) {

  var $injectorMinErr = minErr('$injector');
  var ngMinErr = minErr('ng');

  function ensure(obj, name, factory) {
    return obj[name] || (obj[name] = factory());
  }

  var angular = ensure(window, 'angular', Object);

  // We need to expose `angular.$$minErr` to modules such as `ngResource` that reference it during bootstrap
  angular.$$minErr = angular.$$minErr || minErr;

  return ensure(angular, 'module', function() {
    /** @type {Object.<string, angular.Module>} */
    var modules = {};

    return function module(name, requires, configFn) {
      var assertNotHasOwnProperty = function(name, context) {
        if (name === 'hasOwnProperty') {
          throw ngMinErr('badname', 'hasOwnProperty is not a valid {0} name', context);
        }
      };

      assertNotHasOwnProperty(name, 'module');
      if (requires && modules.hasOwnProperty(name)) {
        modules[name] = null;
      }
      return ensure(modules, name, function() {
        if (!requires) {
          throw $injectorMinErr('nomod', "Module '{0}' is not available! You either misspelled " +
             "the module name or forgot to load it. If registering a module ensure that you " +
             "specify the dependencies as the second argument.", name);
        }

        /** @type {!Array.<Array.<*>>} */
        var invokeQueue = [];

        /** @type {!Array.<Function>} */
        var configBlocks = [];

        /** @type {!Array.<Function>} */
        var runBlocks = [];

        var config = invokeLater('$injector', 'invoke', 'push', configBlocks);

        /** @type {angular.Module} */
        var moduleInstance = {
          // Private state
          _invokeQueue: invokeQueue,
          _configBlocks: configBlocks,
          _runBlocks: runBlocks,

          requires: requires,

          name: name,

          provider: invokeLaterAndSetModuleName('$provide', 'provider'),

          factory: invokeLaterAndSetModuleName('$provide', 'factory'),

          service: invokeLaterAndSetModuleName('$provide', 'service'),

          value: invokeLater('$provide', 'value'),

          constant: invokeLater('$provide', 'constant', 'unshift'),

          decorator: invokeLaterAndSetModuleName('$provide', 'decorator'),

          animation: invokeLaterAndSetModuleName('$animateProvider', 'register'),

          filter: invokeLaterAndSetModuleName('$filterProvider', 'register'),

          controller: invokeLaterAndSetModuleName('$controllerProvider', 'register'),

          directive: invokeLaterAndSetModuleName('$compileProvider', 'directive'),

          config: config,

          run: function(block) {
            runBlocks.push(block);
            return this;
          }
        };

        if (configFn) {
          config(configFn);
        }

        return moduleInstance;

        function invokeLater(provider, method, insertMethod, queue) {
          if (!queue) queue = invokeQueue;
          return function() {
            queue[insertMethod || 'push']([provider, method, arguments]);
            return moduleInstance;
          };
        }

        function invokeLaterAndSetModuleName(provider, method) {
          return function(recipeName, factoryFunction) {
            if (factoryFunction && isFunction(factoryFunction)) factoryFunction.$$moduleName = name;
            invokeQueue.push([provider, method, arguments]);
            return moduleInstance;
          };
        }
      });
    };
  });

}

function publishExternalAPI(angular) {

  angularModule = setupModuleLoader(window);

  angularModule('ng', ['ngLocale'], ['$provide',
    function ngModule($provide) {
      $provide.provider({
        $$sanitizeUri: $$SanitizeUriProvider
      });
      $provide.provider('$compile', $CompileProvider).
        directive({
            a: htmlAnchorDirective,
            // all other directives ....
        }).
        directive({
          ngInclude: ngIncludeFillContentDirective
        }).
        directive(ngAttributeAliasDirectives).
        directive(ngEventDirectives);
      $provide.provider({
        $browser: $BrowserProvider,
        $cacheFactory: $CacheFactoryProvider,
        $controller: $ControllerProvider,
        $document: $DocumentProvider,
        $filter: $FilterProvider,
        $interpolate: $InterpolateProvider,
        $interval: $IntervalProvider,
        $http: $HttpProvider,
        $location: $LocationProvider,
        $log: $LogProvider,
        $parse: $ParseProvider,
        $rootScope: $RootScopeProvider,
        $q: $QProvider,
        $$q: $$QProvider,
        $templateCache: $TemplateCacheProvider,
        $timeout: $TimeoutProvider,
        $window: $WindowProvider,
        $$jqLite: $$jqLiteProvider,
        // and other providers
      });
    }
  ]);
}

function createInjector(modulesToLoad, strictDi) {
  strictDi = (strictDi === true);
  var INSTANTIATING = {},
      providerSuffix = 'Provider',
      path = [],
      loadedModules = new HashMap([], true),
      providerCache = {
        $provide: {
            provider: supportObject(provider),
            factory: supportObject(factory),
            service: supportObject(service),
            value: supportObject(value),
            constant: supportObject(constant),
            decorator: decorator
          }
      },
      providerInjector = (providerCache.$injector =
          createInternalInjector(providerCache, function(serviceName, caller) {
            if (angular.isString(caller)) {
              path.push(caller);
            }
            throw $injectorMinErr('unpr', "Unknown provider: {0}", path.join(' <- '));
          })),
      instanceCache = {},
      instanceInjector = (instanceCache.$injector =
          createInternalInjector(instanceCache, function(serviceName, caller) {
            var provider = providerInjector.get(serviceName + providerSuffix, caller);
            return instanceInjector.invoke(provider.$get, provider, undefined, serviceName);
          }));


  forEach(loadModules(modulesToLoad), function(fn) { if (fn) instanceInjector.invoke(fn); });

  return instanceInjector;

  ////////////////////////////////////
  // $provider
  ////////////////////////////////////

  function supportObject(delegate) {
    return function(key, value) {
      if (isObject(key)) {
        forEach(key, reverseParams(delegate));
      } else {
        return delegate(key, value);
      }
    };
  }

  function provider(name, provider_) {
    assertNotHasOwnProperty(name, 'service');
    if (isFunction(provider_) || isArray(provider_)) {
      provider_ = providerInjector.instantiate(provider_);
    }
    if (!provider_.$get) {
      throw $injectorMinErr('pget', "Provider '{0}' must define $get factory method.", name);
    }
    return providerCache[name + providerSuffix] = provider_;
  }

  function enforceReturnValue(name, factory) {
    return function enforcedReturnValue() {
      var result = instanceInjector.invoke(factory, this);
      if (isUndefined(result)) {
        throw $injectorMinErr('undef', "Provider '{0}' must return a value from $get factory method.", name);
      }
      return result;
    };
  }

  function factory(name, factoryFn, enforce) {
    return provider(name, {
      $get: enforce !== false ? enforceReturnValue(name, factoryFn) : factoryFn
    });
  }

  function service(name, constructor) {
    return factory(name, ['$injector', function($injector) {
      return $injector.instantiate(constructor);
    }]);
  }

  function value(name, val) { return factory(name, valueFn(val), false); }

  function constant(name, value) {
    assertNotHasOwnProperty(name, 'constant');
    providerCache[name] = value;
    instanceCache[name] = value;
  }

  function decorator(serviceName, decorFn) {
    var origProvider = providerInjector.get(serviceName + providerSuffix),
        orig$get = origProvider.$get;

    origProvider.$get = function() {
      var origInstance = instanceInjector.invoke(orig$get, origProvider);
      return instanceInjector.invoke(decorFn, null, {$delegate: origInstance});
    };
  }

  ////////////////////////////////////
  // Module Loading
  ////////////////////////////////////
  function loadModules(modulesToLoad) {
    assertArg(isUndefined(modulesToLoad) || isArray(modulesToLoad), 'modulesToLoad', 'not an array');
    var runBlocks = [], moduleFn;
    forEach(modulesToLoad, function(module) {
      if (loadedModules.get(module)) return;
      loadedModules.put(module, true);

      function runInvokeQueue(queue) {
        var i, ii;
        for (i = 0, ii = queue.length; i < ii; i++) {
          var invokeArgs = queue[i],
              provider = providerInjector.get(invokeArgs[0]);

          provider[invokeArgs[1]].apply(provider, invokeArgs[2]);
        }
      }

      try {
        if (isString(module)) {
          moduleFn = angularModule(module);
          runBlocks = runBlocks.concat(loadModules(moduleFn.requires)).concat(moduleFn._runBlocks);
          runInvokeQueue(moduleFn._invokeQueue);
          runInvokeQueue(moduleFn._configBlocks);
        } else if (isFunction(module)) {
            runBlocks.push(providerInjector.invoke(module));
        } else if (isArray(module)) {
            runBlocks.push(providerInjector.invoke(module));
        } else {
          assertArgFn(module, 'module');
        }
      } catch (e) {
        if (isArray(module)) {
          module = module[module.length - 1];
        }
        if (e.message && e.stack && e.stack.indexOf(e.message) == -1) {
          // Safari & FF's stack traces don't contain error.message content
          // unlike those of Chrome and IE
          // So if stack doesn't contain message, we create a new string that contains both.
          // Since error.stack is read-only in Safari, I'm overriding e and not e.stack here.
          /* jshint -W022 */
          e = e.message + '\n' + e.stack;
        }
        throw $injectorMinErr('modulerr', "Failed to instantiate module {0} due to:\n{1}",
                  module, e.stack || e.message || e);
      }
    });
    return runBlocks;
  }

  ////////////////////////////////////
  // internal Injector
  ////////////////////////////////////

  function createInternalInjector(cache, factory) {

    function getService(serviceName, caller) {
      if (cache.hasOwnProperty(serviceName)) {
        if (cache[serviceName] === INSTANTIATING) {
          throw $injectorMinErr('cdep', 'Circular dependency found: {0}',
                    serviceName + ' <- ' + path.join(' <- '));
        }
        return cache[serviceName];
      } else {
        try {
          path.unshift(serviceName);
          cache[serviceName] = INSTANTIATING;
          return cache[serviceName] = factory(serviceName, caller);
        } catch (err) {
          if (cache[serviceName] === INSTANTIATING) {
            delete cache[serviceName];
          }
          throw err;
        } finally {
          path.shift();
        }
      }
    }

    function invoke(fn, self, locals, serviceName) {
      if (typeof locals === 'string') {
        serviceName = locals;
        locals = null;
      }

      var args = [],
          $inject = createInjector.$$annotate(fn, strictDi, serviceName),
          length, i,
          key;

      for (i = 0, length = $inject.length; i < length; i++) {
        key = $inject[i];
        if (typeof key !== 'string') {
          throw $injectorMinErr('itkn',
                  'Incorrect injection token! Expected service name as string, got {0}', key);
        }
        args.push(
          locals && locals.hasOwnProperty(key)
          ? locals[key]
          : getService(key, serviceName)
        );
      }
      if (isArray(fn)) {
        fn = fn[length];
      }

      // http://jsperf.com/angularjs-invoke-apply-vs-switch
      // #5388
      return fn.apply(self, args);
    }

    function instantiate(Type, locals, serviceName) {
      // Check if Type is annotated and use just the given function at n-1 as parameter
      // e.g. someModule.factory('greeter', ['$window', function(renamed$window) {}]);
      // Object creation: http://jsperf.com/create-constructor/2
      var instance = Object.create((isArray(Type) ? Type[Type.length - 1] : Type).prototype || null);
      var returnedValue = invoke(Type, instance, locals, serviceName);

      return isObject(returnedValue) || isFunction(returnedValue) ? returnedValue : instance;
    }

    return {
      invoke: invoke,
      instantiate: instantiate,
      get: getService,
      annotate: createInjector.$$annotate,
      has: function(name) {
        return providerCache.hasOwnProperty(name + providerSuffix) || cache.hasOwnProperty(name);
      }
    };
  }
}

createInjector.$$annotate = annotate;

if (window.angular.bootstrap) {
  console.log('WARNING: Tried to load angular more than once.');
  return;
}

//try to bind to jquery now so that one can write jqLite(document).ready()
//but we will rebind on bootstrap again.
bindJQuery();

publishExternalAPI(angular);

jqLite(document).ready(function() {
angularInit(document, bootstrap);
});

})(window, document);

!window.angular.$$csp().noInlineStyle && window.angular.element(document.head).prepend('<style type="text/css">@charset "UTF-8";[ng\\:cloak],[ng-cloak],[data-ng-cloak],[x-ng-cloak],.ng-cloak,.x-ng-cloak,.ng-hide:not(.ng-hide-animate){display:none !important;}ng\\:form{display:block;}.ng-animate-shim{visibility:hidden;}.ng-anchor{position:absolute;}</style>');


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