（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

 1 var App = Backbone.Router.extend({
 2     routes: {
 3       "": "index",    // #index
 4       "index": "index",    // #index
 5       "detail": "detail"    // #detail
 6     },
 7     index: function () {
 8       var index = new Index(this.interface);
 9
10    },
11    detail: function () {
12      var detail = new Detail(this.interface);
13
14    },
15    initialize: function () {
16
17    },
18    interface: {
19      forward: function (url) {
20        window.location.href = (‘#‘ + url).replace(/^#+/, ‘#‘);
21      }
22
23    }
24 });

•开启路由控制

Backbone.history.start();

Backbone.history源码分析

history构造函数

 1 var History = Backbone.History = function () {
 2   this.handlers = [];
 3   _.bindAll(this, ‘checkUrl‘);
 4
 5   // Ensure that `History` can be used outside of the browser.
 6   if (typeof window !== ‘undefined‘) {
 7     this.location = window.location;
 8     this.history = window.history;
 9   }
10 };

history.start 函数

 1 start: function(options) {
 2       if (History.started) throw new Error("Backbone.history has already been started");
 3       History.started = true;
 4
 5       // Figure out the initial configuration. Do we need an iframe?
 6       // Is pushState desired ... is it available?
 7       this.options          = _.extend({root: ‘/‘}, this.options, options);
 8       this.root             = this.options.root;
 9       this._wantsHashChange = this.options.hashChange !== false;
10       this._wantsPushState  = !!this.options.pushState;
11       this._hasPushState    = !!(this.options.pushState && this.history && this.history.pushState);
12       var fragment          = this.getFragment();
13       var docMode           = document.documentMode;
14       var oldIE             = (isExplorer.exec(navigator.userAgent.toLowerCase()) && (!docMode || docMode <= 7));
15
16       // Normalize root to always include a leading and trailing slash.
17       this.root = (‘/‘ + this.root + ‘/‘).replace(rootStripper, ‘/‘);
18
19       // 老版本ie以及希望使用hashChange, 使用iframe实现
20       if (oldIE && this._wantsHashChange) {
21         var frame = Backbone.$(‘<iframe src="javascript:0" tabindex="-1">‘);
22         this.iframe = frame.hide().appendTo(‘body‘)[0].contentWindow;
23         this.navigate(fragment);
24       }
25
26       // Depending on whether we‘re using pushState or hashes, and whether
27       // ‘onhashchange‘ is supported, determine how we check the URL state.
28       if (this._hasPushState) {
29         Backbone.$(window).on(‘popstate‘, this.checkUrl);
30       } else if (this._wantsHashChange && (‘onhashchange‘ in window) && !oldIE) {
31         Backbone.$(window).on(‘hashchange‘, this.checkUrl);
32       } else if (this._wantsHashChange) {
33         this._checkUrlInterval = setInterval(this.checkUrl, this.interval);
34       }              /* 取决于选择hash还是pushState  　　　　　　如果使用 pushState，调用方法           Backbone.history.start({ pushState: true });           */
35
36       // Determine if we need to change the base url, for a pushState link
37       // opened by a non-pushState browser.
38       this.fragment = fragment;
39       var loc = this.location;
40
41       // Transition from hashChange to pushState or vice versa if both are
42       // requested.
43       if (this._wantsHashChange && this._wantsPushState) {
44
45         // If we‘ve started off with a route from a `pushState`-enabled
46         // browser, but we‘re currently in a browser that doesn‘t support it...
47         if (!this._hasPushState && !this.atRoot()) {
48           this.fragment = this.getFragment(null, true);
49           this.location.replace(this.root + ‘#‘ + this.fragment);
50           // Return immediately as browser will do redirect to new url
51           return true;
52
53         // Or if we‘ve started out with a hash-based route, but we‘re currently
54         // in a browser where it could be `pushState`-based instead...
55         } else if (this._hasPushState && this.atRoot() && loc.hash) {
56           this.fragment = this.getHash().replace(routeStripper, ‘‘);
57           this.history.replaceState({}, document.title, this.root + this.fragment);
58         }
59
60       }
61
62       if (!this.options.silent) return this.loadUrl();
63     }

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;
}