javascript 如何将新项目“推”到数组的中间？

How to "push' a new item to the middle of an array?

提问by Hey24sheep

I just completed section1, and noticed that there isn't a method covered on how to push an item to the a specific location of the array. For example, if I wanted the array to show

我刚刚完成了第 1 部分，并注意到没有涵盖如何将项目推送到数组的特定位置的方法。例如，如果我希望数组显示

var suits = ["hearts","clubs","Brooks Brothers", "diamonds","spades"]

How would I be able to push in "Brooks Brothers" into the position [2] of the array suits, and shift the rest 1 down? Is there a built-in function in javascript similar to push that would enable me to do this?

我如何才能将“布鲁克斯兄弟”推入阵列套装的位置 [2]，并将其余的 1 向下移动？javascript 中是否有类似于 push 的内置函数可以让我做到这一点？

I suppose I could always, with some diffculty:

我想我总是可以，但有些困难：

function add (item, position){
    var length = suits.length;
    for(i = length -1; i >= position; i--){
        suits[length] = suits[i];
        length--;
    };
    suits[position] = item;
};

add("Brooks Brothers",2) //to add it to the middle

回答by felixmosh

You can use Array.splicein order to insert item to Array at specific place.

您可以使用Array.splice以将项目插入到特定位置的 Array 中。

const suits = ["hearts", "clubs", "Brooks Brothers", "diamonds", "spades"];

suits.splice(2, 0, 'newItem');

console.log(suits);

回答by CodeIt

There are no inbuilt function for this in JavaScript but you can simply do this using splice

JavaScript 中没有为此内置函数，但您可以使用splice简单地做到这一点

var suits = ["hearts","clubs","Brooks Brothers", "diamonds","spades"];

suits.splice(2, 0, "Brooks Brothers");

This would insert item X to index 2 of array suits, ["hearts", "clubs", "Brooks Brothers", "Brooks Brothers", "diamonds", "spades"]

这会将项目 X 插入数组套装的索引 2， ["hearts", "clubs", "Brooks Brothers", "Brooks Brothers", "diamonds", "spades"]

Syntax

句法

<array-name>.splice(<position-to-insert-items>,0,<item-1>,<item-2>,..,<item-n>)

Always pass second second argument as 0, because we don't want to delete any item from the array while splicing.

始终将第二个第二个参数传递为 0，因为我们不想在拼接时从数组中删除任何项目。

回答by Hey24sheep

You can use the built-in SpliceFunction

您可以使用内置的拼接功能

The splice()method changes the contents of an array by removing existing elements and/or adding new elements.

的拼接（）方法通过去除现有元件和/或添加新元素改变的数组的内容。

1- To insert single value

1- 插入单个值

var suits = ["hearts","clubs","Brooks Brothers", "diamonds","spades"];

//1st param is insert index = 2 means insert at index 2
//2nd param is delete item count = 0 means delete 0 elements
//3rd param is new item that you want to insert
suits.splice(2, 0 , "Test");

console.log(suits);

2- To insert array into your suits array

2- 将数组插入您的西装数组

var suits = ["hearts","clubs","Brooks Brothers", "diamonds","spades"];

var newSuitsToInsert = ["test1", "test2","hello"];

    //1st param is insert index = 2 means insert at index 2
    //2nd param is delete item count = 0 means delete 0 elements
    //3rd param is new item that you want to insert
    //... is the spread syntax which will expand elements as one
    suits.splice(2, 0 , ...newSuitsToInsert);

    console.log(suits);

回答by Sanjay Kumar Singh

You should use splicefunction

您应该使用拼接功能

arr.splice(index, 0, item);will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert).

arr.splice(index, 0, item);将 item 插入到指定索引处的 arr （先删除 0 个项目，也就是说，它只是一个插入）。

var suits = ["hearts","clubs","Brooks Brothers", "diamonds","spades"]

suits.splice(2, 0, "somevalue");

console.log(suits);