vue双向数据绑定知识点总结(3)

function xhVue(options){
 
}

function xhVue(options){
 this._init(options);
}
xhVue.prototype._init = function(options){
 this.$options = options; // options为使用时传入的结构体；包括el，data，methods等
 this.$el = document.querySelector(options.el); // el就是#app，this.$el是id为app的Element元素
 this.$data = options.data; // this.$data = {number:0}
 this.$methods = options.methods; // increment
}

xhVue.prototype._xhob = function(obj){ // obj = {number:0}
 var value;
 for(key in obj){
  if(obj.hasOwnProperty(ket)){
   value = obj[key];
   if(typeof value === 'object'){
    this._xhob(value);
   }
   Object.defineProperty(this.$data,key,{
    enumerable:true,
    configurable:true,
    get:function(){
     return value;
    },
    set:function(newVal){
     if(value !== newVal){
      value = newVal;
     }
    }
   })
  }
 }
}
xhVue.prototype._init = function(options){
 this.$options = options;
 this.$el = document.querySelector(options.el);
 this.$data = options.data;
 this.$method = options.methods;
 this._xhob(this.$data);
}

function xhWatcher(name,el,vm,exp,attr){
 this.name = name; // 指令名称；对于文本节点；例如text
 this.el = el; // 指令对应DOM元素
 this.vm = vm; // 指令所属vue实例
 this.exp = exp; // 指令对应的值；例如number
 this.attr = attr; // 绑定的属性值；例如innerHTML
 this.update();
}
xhWatcher.prototype.update = function(){
 this.el[this.attr] = this.vm.$data[this.exp];
 // 例如h3的innerHTML = this.data.number;当numner改变则会触发本update方法；保证对应的DOM实时更新
}

// 给init的时候增加一个对象来存储model和view的映射关系；也就是我们前面定义的xhWatcher的实例；当model发生变化时；我们会触发其中的指令另其更新；保证了view也同时更新
xhVue.prototype._init = function(options){
 this.$options = options;
 this.$el = document.querySelector(options.el);
 this.$data = options.data;
 this.$method = options.methods;
 
 this._binding = {}; // _binding
 this._xhob(this.$data);
}
// 通过init出来的_binding
xhVue.prototype._xhob = function(obj){ // obj = {number:0}
 var value;
 for(key in obj){
  if(obj.hasOwnProperty(ket)){
   this._binding[key] = {
    // _binding = {number:_directives:[]}
    _directives = []
   }
   value = obj[key];
   if(typeof value === 'object'){
    this._xhob(value);
   }
   var binding = this._binding[key];
   Object.defineProperty(this.$data,key,{
    enumerable:true,
    configurable:true,
    get:function(){
     return value;
    },
    set:function(newVal){
     if(value !== newVal){
      value = newVal;
      // 当number改变时；触发_binding[number]._directives中已绑定的xhWatcher更新
      binding._directives.forEach(function(item){
       item.update(); 
      });
     }
    }
   })
  }
 }
}