ES6知识点整理之Proxy的应用实例详解

var obj = {name:'Joh'};
var proxy = new Proxy(obj, {
 get (target, key) {
  return 'test1';
 },
 set (target, key, value) {
  target[key] = value
 }
});
console.log(proxy.name); // test1 进行get取值
proxy.name = 'test2'; // 进行set设置
console.log(obj.name); // test2

var obj = {name:'Joh',group:'g1',_type:'student'};
var proxy = new Proxy(obj, {
 get (target, key) {
  if(key[0]!== '_') {
   // return Reflect.get(target,key); // 效果等同于下面的return语句
   return target[key];
  };
 },
 set (target, key, value) {
  if(key[0]!== '_') {
   // Reflect.set(target,key,value);
   return target[key] = value;
  }
 },
 deleteProperty(target, key) {
  // 业务逻辑
  if(key[0] !== '_') {
   // Reflect.deleteProperty(target, key);
   delete target[key];
  }
 }
});
console.log(proxy.name); // Joh
console.log(obj.name); // Joh
proxy.name = 'Lily'; // 在非严格模式下的赋值操作，严格模式将会报错
console.log(obj.name); // Lily
delete proxy.name; // 未能成功删除，因为上面内部有判断
console.log(obj.name); // undefined 成功删除
delete proxy.group;
console.log(obj.group); // undefined 成功删除
delete proxy._type;
console.log(obj._type); // student
proxy.color='red';
console.log(obj.color); // red

var obj = {name:"Joh",_name:"Lily"};
var proxy = new Proxy(obj, {
 has(target, key) {
  if(key[0] === '_'){
   return false;
  } else {
   return key in target;
  }
 }
});
console.log('has name attr: ', 'name' in proxy); // has name attr: true
console.log('has _name attr: ', '_name' in proxy); // has _name attr: false

var obj = {name:"Joh",_name:"Lily", age:10, group:"g1"};
var proxy = new Proxy(obj, {
 ownKeys (target) {
  return Reflect.ownKeys(target).filter(key => key[0] !== '_');
 }
});
for(var k in proxy) {
 console.log(k); // 分别输出 name age group 过滤了 _name
}

function test() {
 console.log('hello world');
}
var proxyFun = new Proxy(test,{
 apply(target,ctx,args) {
  console.log('proxy apply');
  return Reflect.apply(target,ctx,args);
 }
});
proxyFun(); // 分别输出 proxy apply 和 hello world
// proxyFun.apply(); // 同样，分别输出 proxy apply 和 hello world
// proxyFun.call(); // 同样，分别输出 proxy apply 和 hello world

function User() {
 console.log('this is a contructor');
}
var ClassProxy = new Proxy(User, {
 construct(target,args) {
  console.log('proxy construct');
  return Reflect.construct(target,args);
 }
});
new ClassProxy(); // 分别输出 proxy construct 和 this is a contructor