Javascript 删除索引后的所有项目

Remove all items after an index

提问by Starkers

I have an array:

我有一个数组：

array = ['mario','luigi','kong']

I call its splicefunction to remove all items before an index:

我调用它的splice函数来删除索引之前的所有项目：

array.splice(1) //-> ['luigi','kong']

I'm just wondering if there is a function similar to spliceto remove all items after an index:

我只是想知道是否有类似于splice的函数来删除索引后的所有项目：

pseudo code

伪代码

array.mirrorsplice(1) //-> ['mario','luigi']

回答by dandavis

Use Array.lengthto set a new size for an array, which is faster than Array.spliceto mutate:

使用Array.length设置新的大小的数组，这是比快Array.splice变异：

var array = ['mario','luigi','kong', 1, 3, 6, 8];
array.length=2;
alert(array); // shows "mario,luigi";

Why is it faster? Because .splicehas to create a new array containing all the removed items, whereas .lengthcreates nothing and "returns" a number instead of a new array.

为什么它更快？因为.splice必须创建一个包含所有已删除项目的新数组，而.length什么也不创建并“返回”一个数字而不是一个新数组。

To address .spliceusage, you can feed it a negative index, along with a huge number to chop off the end of an array:

为了解决.splice使用问题，你可以给它一个负索引，以及一个巨大的数字来切断数组的末尾：

var array = ['mario','luigi','kong'];
array.splice(-1, 9e9); 
alert(array); // shows "mario,luigi";

回答by sha-1

Though assigning a shorter value to the array length(as @dandavis said) is the fastest and simplest way to remove trailing element from an array, you can also do that using a similar method like splicewhich is known as slice. Like following:

虽然为数组长度分配一个较短的值（如@dandavis 所说）是从数组中删除尾随元素的最快和最简单的方法，但您也可以使用类似的方法来做到这一点，例如splice，称为slice。像下面这样：

array = ['mario', 'luigi', 'kong'];

array = array.slice(0, 2); //Need to assign it to the same or another variable

console.log(array); //["mario", "luigi"]

As you can see you need to store the returned value from slicemethod. To understand 'why', here are the major distinction between sliceand splicemethod:

如您所见，您需要存储slice方法的返回值。要理解“为什么”，以下是slice和splice方法之间的主要区别：

• The splice()method returns the removed item(s) in an array and slice()method returns the selected element(s) in an array, as a new array object.
• The splice()method changes the original array and slice()method doesn't change the original array.

• 该splice()方法返回数组中删除的项目，slice()方法返回数组中的选定元素，作为新的数组对象。
• 该splice()方法更改原始数组，slice()方法不更改原始数组。

回答by Ni?o Angelo Orlanes Lapura

To removeall items after an index:

要删除所有项目的索引后：

var array = ['mario','luigi','kong'],
index = 1; // your index here
array.splice(index + 1, array.length - (index + 1) );
// 3 - (1+1) = 1
// 1 is the remaining number of element(s) in array
// hence, splice 1 after index

Result:

结果：

['mario', 'luigi']

You need to +1 since splicestarts removing at the index.

您需要 +1，因为splice开始在索引处删除。

回答by Yagnesh Khamar

You can use splice. Here is a demo.

您可以使用拼接。这是一个演示。

var array = ['mario','luigi','kong']

To remove all the elements after an index:

删除索引后的所有元素：

var removedElement = array.splice(index, array.length)

removedElementwill have the list of elements removed from the array.

removeElement将从数组中删除元素列表。

example:

例子：

let index = 2;
var removedElement = array.splice(2, array.length); 
removedElement = ["kong"];
array = ["mario", "luigi"];