对象的基本操作

  var mc = {};
  Object.defineProperty(mc,"name",{value:"jlp",writable:false,enumerable:true});
  mc.age = "16";

for(x in mc){
console.log(x);
console.log(mc[x]);
}

var arr = []; // var = new Array();
arr = Object.keys(mc); // 遍历所有属性

boolean = "name" in mc //true  or false

boolean = mc.hasOwnProperty("name");

  var mc = {name:"jlp",age:"16"};
  if (Object.getOwnPropertyDescriptor(mc,"age").configurable) 
  {
     delete mc.age;
  }