Tips for inserting elements at specified positions at specific indexes in JS arrays_javascript tips

How to insert an element at a specified position at a specific index in a JS array?

Requirement: Insert an element into an existing array at a specific index. It sounds easy and common, but it takes a little time to research it.

// 原来的数组
var array = ["one", "two", "four"];
// splice(position, numberOfItemsToRemove, item)
// 拼接函数(索引位置, 要删除元素的数量, 元素)
array.splice(2, 0, "three"); // 
array; // 现在数组是这个样子 ["one", "two", "three", "four"]

If you are not averse to extending native JavaScript, you can add this method to the Array prototype:

Array.prototype.insert = function (index, item) {
this.splice(index, 0, item);
}; 

At this time, you can call it like this:

var nums = ["one", "two", "four"];
nums.insert(2, 'three'); // 注意数组索引, [0,1,2..]
array // ["one", "two", "three", "four"]