vue源码学习之Object.defineProperty 对数组监听

var a={};
bValue=1;
Object.defineProperty(a,"b",{
  set:function(value){
    bValue=value;
    console.log("setted");
  },
  get:function(){
    return bValue;
  }
});
a.b;//1
a.b=[];//setted
a.b=[1,2,3];//setted
a.b[1]=10;//无输出
a.b.push(4);//无输出
a.b.length=5;//无输出
a.b;//[1,10,3,4,undefined];

var arrayPush = {};
(function(method){
  var original = Array.prototype[method];
  arrayPush[method] = function() {
    // this 指向可通过下面的测试看出
    console.log(this);
    return original.apply(this, arguments)
  };
})('push');

var testPush = [];
testPush.__proto__ = arrayPush;
// 通过输出，可以看出上面所述 this 指向的是 testPush
// []
testPush.push(1);
// [1]
testPush.push(2);

var arrayProto = Array.prototype
var arrayMethods = Object.create(arrayProto)

;[
 'push',
 'pop',
 'shift',
 'unshift',
 'splice',
 'sort',
 'reverse'
].forEach(function(item){
  Object.defineProperty(arrayMethods,item,{
    value:function mutator(){
      //缓存原生方法，之后调用
      console.log('array被访问');
      var original = arrayProto[item]  
      var args = Array.from(arguments)
    original.apply(this,args)
      // console.log(this);
    },
  })
})

function Observer(data){
  this.data = data;
  this.walk(data);
}

var p = Observer.prototype;
var arrayProto = Array.prototype
var arrayMethods = Object.create(arrayProto)

;[
 'push',
 'pop',
 'shift',
 'unshift',
 'splice',
 'sort',
 'reverse'
].forEach(function(item){
  Object.defineProperty(arrayMethods,item,{
    value:function mutator(){
      //缓存原生方法，之后调用
      console.log('array被访问');
      var original = arrayProto[item]  
      var args = Array.from(arguments)
    original.apply(this,args)
      // console.log(this);
    },
  })
})

p.walk = function(obj){
  var value;
  for(var key in obj){
    // 通过 hasOwnProperty 过滤掉一个对象本身拥有的属性 
    if(obj.hasOwnProperty(key)){
      value = obj[key];
      // 递归调用 循环所有对象出来
      if(typeof value === 'object'){
        if (Array.isArray(value)) {
          var augment = value.__proto__ ? protoAugment : copyAugment 
          augment(value, arrayMethods, key)
          observeArray(value)
        }
        new Observer(value);
      }
      this.convert(key, value);
    }
  }
};

p.convert = function(key, value){
  Object.defineProperty(this.data, key, {
    enumerable: true,
    configurable: true,
    get: function(){
      console.log(key + '被访问');
      return value;
    },
    set: function(newVal){
      console.log(key + '被修改，新' + key + '=' + newVal);
      if(newVal === value) return ;
      value = newVal;
    }
  })
}; 

var data = {
  user: {
    // name: 'zhangsan',
    age: function(){console.log(1)}
  },
  apg: [{'a': 'b'},2,3]
}

function observeArray (items) {
  for (var i = 0, l = items.length; i < l; i++) {
    observe(items[i])
  }
}

//数据重复Observer
function observe(value){
  if(typeof(value) != 'object' ) return;
  var ob = new Observer(value)
   return ob;
}

//辅助方法
function def (obj, key, val) {
 Object.defineProperty(obj, key, {
  value: val,
  enumerable: true,
  writable: true,
  configurable: true
 })
}

// 兼容不支持__proto__的方法
//重新赋值Array的__proto__属性
function protoAugment (target,src) {
 target.__proto__ = src
}
//不支持__proto__的直接修改相关属性方法
function copyAugment (target, src, keys) {
 for (var i = 0, l = keys.length; i < l; i++) {
  var key = keys[i]
  def(target, key, src[key])
 }
}

var app = new Observer(data);
// data.apg[2] = 111;
data.apg.push(5);
// data.apg[0].a = 10;
// console.log(data.apg);