在 JavaScript 中删除数组元素 - 删除 vs 拼接 [英] Deleting array elements in JavaScript - delete vs splice

问题描述

使用delete<有什么区别数组元素上的/code> 运算符，而不是使用 Array.splice 方法?

What is the difference between using the delete operator on the array element as opposed to using the Array.splice method?

例如:

myArray = ['a', 'b', 'c', 'd'];

delete myArray[1];
//  or
myArray.splice (1, 1);

如果我可以像删除对象一样删除数组元素，为什么还要使用 splice 方法?

Why even have the splice method if I can delete array elements like I can with objects?

推荐答案

delete 将删除对象属性，但不会重新索引数组或更新其长度.这使它看起来好像是未定义的:

delete will delete the object property, but will not reindex the array or update its length. This makes it appears as if it is undefined:

> myArray = ['a', 'b', 'c', 'd']
  ["a", "b", "c", "d"]
> delete myArray[0]
  true
> myArray[0]
  undefined

请注意，它实际上并未设置为值 undefined，而是从数组中删除了该属性，使其出现未定义.Chrome 开发工具通过在记录数组时打印 empty 来明确区分.

Note that it is not in fact set to the value undefined, rather the property is removed from the array, making it appear undefined. The Chrome dev tools make this distinction clear by printing empty when logging the array.

> myArray[0]
  undefined
> myArray
  [empty, "b", "c", "d"]

myArray.splice(start, deleteCount) 实际上是删除元素，重新索引数组，并改变其长度.

myArray.splice(start, deleteCount) actually removes the element, reindexes the array, and changes its length.

> myArray = ['a', 'b', 'c', 'd']
  ["a", "b", "c", "d"]
> myArray.splice(0, 2)
  ["a", "b"]
> myArray
  ["c", "d"]

这篇关于在 JavaScript 中删除数组元素 - 删除 vs 拼接的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！