Comprendre brièvement le code source du modèle Model et la vue des connaissances Backbone.js_Basic

 var People = Backbone.Model.extend({
     
 });

 var Man = People.extend({

 });

  var Model = Backbone.Model = function(attributes, options) {
     var attrs = attributes || {};
     options || (options = {});
     this.cid = _.uniqueId('c');
     this.attributes = {};
     if (options.collection) this.collection = options.collection;
     if (options.parse) attrs = this.parse(attrs, options) || {};
     attrs = _.defaults({}, attrs, _.result(this, 'defaults'));
     this.set(attrs, options);
     this.changed = {};
     this.initialize.apply(this, arguments);
   };

model.set(attributes, [options])

  set: function(key, val, options) {
     //......

      // key值可以是键值对，也可以是一个字符串,将赋值传入attrs属性中  
    if (typeof key === 'object') {
     attrs = key;
     options = val;
    } else {
     (attrs = {})[key] = val;
    }

   // ....

    //对设置的值进行校验 
      if (!this._validate(attrs, options)) return false;
    unset = options.unset; // unset为true时会删除设置的值,unset方法就是通过 set(key,val,{unset:true})去实现的
   
    //当对象正在被被设置的时候，不给 previousAttributes 赋值
    if (!changing) {
     this._previousAttributes = _.clone(this.attributes);
     this.changed = {};
    }
 
    current = this.attributes, prev = this._previousAttributes;
 
    //如果对Id进行了设置，则对对象的id属性也进行改变
    if (this.idAttribute in attrs) this.id = attrs[this.idAttribute];
 

    //进行 设置或者是删除操作
    for (attr in attrs) {
     val = attrs[attr];
     if (!_.isEqual(current[attr], val)) changes.push(attr);
     if (!_.isEqual(prev[attr], val)) {
      this.changed[attr] = val;//为model的changed进行设置
     } else {
      delete this.changed[attr];
     }
     unset ? delete current[attr] : current[attr] = val;//如果unset被设置成true了，则进行删除操作
    }
 
    //在silent不为false 的情况下，进行change:attr事件发送
    if (!silent) {
     if (changes.length) this._pending = options;
     for (var i = 0, l = changes.length; i < l; i++) {
      this.trigger('change:' + changes[i], this, current[changes[i]], options);
     }
    }
 

    //触发change事件
    if (changing) return this;
    if (!silent) {
     while (this._pending) {
      options = this._pending;
      this._pending = false;
      this.trigger('change', this, options);
     }
    }
    this._pending = false;
    this._changing = false;
    return this;
   
  }

model.save([attributes], [options])

  save: function(key, val, options) {     
    // ......
 

 
    //当设置了wait属性true的时候 , save方法先不执行set方法(不触发change事件),只执行validate
    if (attrs && !options.wait) {
     if (!this.set(attrs, options)) return false;
    } else {
     if (!this._validate(attrs, options)) return false;
    }

    //如果wait为true,设置this.attributes
    if (attrs && options.wait) {
     this.attributes = _.extend({}, attributes, attrs);
    }
 

    // .....
   
    var model = this;
    var success = options.success;
    options.success = function(resp) {
     // Ensure attributes are restored during synchronous saves.
     model.attributes = attributes;
     var serverAttrs = model.parse(resp, options);
     //如果wait为true , 那么会在请求返回之后才进行set操作
     if (options.wait) serverAttrs = _.extend(attrs || {}, serverAttrs);
     if (_.isObject(serverAttrs) && !model.set(serverAttrs, options)) {
      return false;
     }
     if (success) success(model, resp, options);
     //触发 sync 事件
     model.trigger('sync', model, resp, options);
    };

    //生成XHR onerror 回调函数
    wrapError(this, options);
    //选择方法
    method = this.isNew() ? 'create' : (options.patch ? 'patch' : 'update');
    if (method === 'patch') options.attrs = attrs;
    xhr = this.sync(method, this, options);
 
    // Restore attributes.
    if (attrs && options.wait) this.attributes = attributes;
    //返回xhr对象
    return xhr;
  }