SOURCE

var list = [8,7,6,5,4]
list.map((i,index,arr)=>{console.log(i,index,arr)})

var data = {};
data = {name:'哈哈',num:5}
console.log(data);

var proxy = new Proxy(data, {
  set: function(target, property) {
      console.log('劫持到了')
    if (property in target) {
        
      return target[property];
    } else {
      throw new ReferenceError("Property \"" + property + "\" does not exist.");
    }
  }
});
proxy.name = '嘿嘿';

var target = {};
var handler = {};
var proxy = new Proxy(target, handler);
proxy.a = 'b';
target.a // "b"