javascript中object的运算符操作使用

javascript中object的运算符操作使用

1:delete

使用：

delete obj.x

var obj = {x:1}
obj.x//1
delete obj.x
obj.x//undefined

2:defineProperty

使用：

var obj = {};

Object.defineProperty(obj,"x",{
	configurable:false,
	value:1
})

delete obj.x //false
obj.x//1

3:in

使用：

window.x = 1;
"x" in window //true

4: instanceof

{} instanceof Object

5: typeof

typeof 123

6:new && hasOwnProperty

function Perosn(){}
Person.prototype.x = 1;
var person = new Person();
person.x //1
person.hasOwnProperty("x")//false
person.__proto__.hasOwnProperty("x")//true

7:this

var obj = {
	func:function(){
		return this;
	}
}
obj.func()//Object()

8:void

void 0 //undefined
void(0) //undefined