vue源碼學習之Object.defineProperty 對數組監聽

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;//無

var arrayPush = {};
(function(method){
 var original = Array.prototype[method];
 arrayPush[method] = function() {
 // this 指向可通過下面的測試看出
 console.log(this);
 return original.apply(this, arguments)
 };
})('push');

var testPush = [];
testPush.__proto__ = arrayPush;
// 通過

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(){
 //緩存原生方法，之后調用
 console.log('array被訪問');
 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(){
 //緩存原生方法，之后調用
 console.log('array被訪問');
 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){
 // 通過 hasOwnProperty 過濾掉一個對象本身擁有的屬性 
 if(obj.hasOwnProperty(key)){
 value = obj[key];
 // 遞歸調用 循環所有對象出來
 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 + '被訪問');
 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])
 }
}

//數據重復Observer
function observe(value){
 if(typeof(value) != 'object' ) return;
 var ob = new Observer(value)
 return ob;
}

//輔助方法
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
//重新賦值Array的__proto__屬性
function protoAugment (target,src) {
 target.__proto__ = src
}
//不支持__proto__的直接修改相關屬性方法
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);