JavaScript 值删除对象（Object）的属性——delete

原网址：https://blog.csdn.net/weixin_43553701/article/details/90757945

删除对象属性的方法

JS中如何删除对象中的某一属性

var obj={
    name: 'zhagnsan',
    age: 19 
}
delete obj.name //true
typeof obj.name //undefined

通过delete操作符，可以实现兑现属性的删除操作，返回值是布尔。

delete可以删除什么？

1. 变量

var name ='zs'  //已声明的变量
delete name  //false
console.log(typeof name)  //String

age = 19  //未声明的变量
delete age     //true
typeof age //undefined

this.val = 'fds'  //window下的变量
delete this.val      //true
console.log(typeof this.val)  //undefined

 已声明的变量在windows下可删除，未声明的变量不可删除。

2.函数

var fn = function(){}  //已声明的函数
delete fn    //false
console.log(typeof fn)  //function

fn = function(){}  //未声明的函数
delete fn    //true
console.log(typeof fn)  //undefined

 3.数组

var arr = ['1','2','3']  ///已声明的数组
delete arr    //false
console.log(typeof arr)  //object

arr = ['1','2','3']  //未声明的数组
delete arr   //true    
console.log(typeof arr)   //undefined

var arr = ['1','2','3']   //已声明的数组
delete arr[1]  //true
console.log(arr)   //['1','empty','3'] 

4. 对象

var person = {
  height: 180,
  long: 180,
  weight: 180,
  hobby: {
    ball: 'good',
    music: 'nice'
  }
}
delete person  ///false
console.log(typeof person)   //object

var person = {
  height: 180,
  long: 180,
  weight: 180,
  hobby: {
    ball: 'good',
    music: 'nice'
  }
}
delete person.hobby  ///true
console.log(typeof person.hobby)  //undefined

 已声明的对象不可删除，对象中的对象属性可删除。