（六）backbone - API学习 - Backbone路由

Backbone路由本质

Backbone路由分为两个大块，Router以及History
用户在Router中定义相关规则，然后开启history.start进行路由监控，执行默认的回调
所以，Router本身除了定义路由规则，全部调用的是Backbone.history的方法
Backbone.History的主要关注点事实上是 popstate(hashChange)的回调checkUrl，无论我们触发navigate或者点击浏览器后退
皆是进入此入口，再回调至Router定义的回调，从而实现相关逻辑

•创建规则

 var App = Backbone.Router.extend({
     routes: {
       "": "index",    // #index
       "index": "index",    // #index
       "detail": "detail"    // #detail
     },
     index: function () {
       var index = new Index(this.interface);

    },
    detail: function () {
      var detail = new Detail(this.interface);

    },
    initialize: function () {

    },
    interface: {
      forward: function (url) {
        window.location.href = ('#' + url).replace(/^#+/, '#');
      }

    }
 });

•开启路由控制

Backbone.history.start();

Backbone.history源码分析

history构造函数

 var History = Backbone.History = function () {
   this.handlers = [];
   _.bindAll(this, 'checkUrl');

   // Ensure that `History` can be used outside of the browser.
   if (typeof window !== 'undefined') {
     this.location = window.location;
     this.history = window.history;
   }
 };

history.start 函数

 start: function(options) {
       if (History.started) throw new Error("Backbone.history has already been started");
       History.started = true;

       // Figure out the initial configuration. Do we need an iframe?
       // Is pushState desired ... is it available?
       this.options          = _.extend({root: '/'}, this.options, options);
       this.root             = this.options.root;
       this._wantsHashChange = this.options.hashChange !== false;
       this._wantsPushState  = !!this.options.pushState;
       this._hasPushState    = !!(this.options.pushState && this.history && this.history.pushState);
       var fragment          = this.getFragment();
       var docMode           = document.documentMode;
       var oldIE             = (isExplorer.exec(navigator.userAgent.toLowerCase()) && (!docMode || docMode <= 7));

       // Normalize root to always include a leading and trailing slash.
       this.root = ('/' + this.root + '/').replace(rootStripper, '/');

       // 老版本ie以及希望使用hashChange, 使用iframe实现
       if (oldIE && this._wantsHashChange) {
         var frame = Backbone.$('<iframe src="javascript:0" tabindex="-1">');
         this.iframe = frame.hide().appendTo('body')[0].contentWindow;
         this.navigate(fragment);
       }

       // Depending on whether we're using pushState or hashes, and whether
       // 'onhashchange' is supported, determine how we check the URL state.
       if (this._hasPushState) {
         Backbone.$(window).on('popstate', this.checkUrl);
       } else if (this._wantsHashChange && ('onhashchange' in window) && !oldIE) {
         Backbone.$(window).on('hashchange', this.checkUrl);
       } else if (this._wantsHashChange) {
         this._checkUrlInterval = setInterval(this.checkUrl, this.interval);
       }   
           /* 取决于选择hash还是pushState 
 　　　　　　如果使用 pushState，调用方法
           Backbone.history.start({ pushState: true });
           */

       // Determine if we need to change the base url, for a pushState link
       // opened by a non-pushState browser.
       this.fragment = fragment;
       var loc = this.location;

       // Transition from hashChange to pushState or vice versa if both are
       // requested.
       if (this._wantsHashChange && this._wantsPushState) {

         // If we've started off with a route from a `pushState`-enabled
         // browser, but we're currently in a browser that doesn't support it...
         if (!this._hasPushState && !this.atRoot()) {
           this.fragment = this.getFragment(null, true);
           this.location.replace(this.root + '#' + this.fragment);
           // Return immediately as browser will do redirect to new url
           return true;

         // Or if we've started out with a hash-based route, but we're currently
         // in a browser where it could be `pushState`-based instead...
         } else if (this._hasPushState && this.atRoot() && loc.hash) {
           this.fragment = this.getHash().replace(routeStripper, '');
           this.history.replaceState({}, document.title, this.root + this.fragment);
         }

       }

       if (!this.options.silent) return this.loadUrl();
     }

统一入口 loadUrl

loadUrl: function (fragmentOverride) {
  var fragment = this.fragment = this.getFragment(fragmentOverride);
  var matched = _.any(this.handlers, function (handler) {      // handlers是routes定义的集合，实例化Router时导入
    if (handler.route.test(fragment)) {
      handler.callback(fragment);
      return true;
    }
  });
  return matched;
}