JavaScript 值刪除對象（Object）的屬性——delete

原網址：https://blog.csdn.net/weixin_43553701/article/details/90757945

刪除對象屬性的方法

JS中如何刪除對象中的某一屬性

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

通過delete操作符，可以實現兌現屬性的刪除操作，返回值是布爾。

delete可以刪除什么？

1. 變量

var name ='zs'  //已聲明的變量
delete name  //false
console.log(typeof name)  //String

age = 19  //未聲明的變量
delete age     //true
typeof age //undefined

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

 已聲明的變量在windows下可刪除，未聲明的變量不可刪除。

2.函數

var fn = function(){}  //已聲明的函數
delete fn    //false
console.log(typeof fn)  //function

fn = function(){}  //未聲明的函數
delete fn    //true
console.log(typeof fn)  //undefined

 3.數組

var arr = ['1','2','3']  ///已聲明的數組
delete arr    //false
console.log(typeof arr)  //object

arr = ['1','2','3']  //未聲明的數組
delete arr   //true    
console.log(typeof arr)   //undefined

var arr = ['1','2','3']   //已聲明的數組
delete arr[1]  //true
console.log(arr)   //['1','empty','3'] 

4. 對象

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

 已聲明的對象不可刪除，對象中的對象屬性可刪除。