javascript - Get first and last value from array - Stack Overflow

admin管理员组

文章数量:1344968

I have a an array being passed to me which is something like

var arr = ["A", "B", "C"];

What I am trying to achieve is to only get the first and last value so it should look like

var arr = ["A", "C"];

I'm not how to achieve this using splice because when I do

arr.splice(I am not sure what numbers to put here).forEach(function (element) {
        console.log(element);
});

Can someone tell me how to achieve this please.

I have a an array being passed to me which is something like

var arr = ["A", "B", "C"];

What I am trying to achieve is to only get the first and last value so it should look like

var arr = ["A", "C"];

I'm not how to achieve this using splice because when I do

arr.splice(I am not sure what numbers to put here).forEach(function (element) {
        console.log(element);
});

Can someone tell me how to achieve this please.

• javascript

Share Improve this question Follow asked Oct 27, 2017 at 10:07 IzzyIzzy 6,87688 gold badges4343 silver badges9292 bronze badges 1

• 2 For first value use arr[0] and for last use arr[arr.length - 1]; – Harsh Patel Commented Oct 27, 2017 at 10:08

Add a ment  | 

4 Answers 4

Sorted by: Reset to default 7

What I am trying to achieve is to only get the first and last value so it should look like

Simply

arr.splice( 1, arr.length - 2 );

Demo

var arr = ["A", "B", "C"];

arr.splice(1, arr.length - 2);

console.log(arr);

For the first element you know arr[0] For the last element arr[arr.length -1] so let newAr = [arr[0], arr[arr.length -1]]

Considering you are trying to get values between the first and the last value of your array removed, you need to pass splice some value indicating how many elements your array contains.

this is why you should consider using:

var arr = ["A", "B", "C"];
arr.splice(1, arr.length - 2);

Explanation:

Splice takes at least 2 variables (this goes only if you use splice to remove items), the first being the position of the string at which you want to start removing items, and the second the number of items you actually want to remove.

To translate this simple line with words, it says After the first element of the array, remove the next X items with X being the length of the array minus the first and the last element (this is why you have the "-2").

Hope i explained properly,

cheers

You can do

var arr = ["A", "B", "C"];

console.log(arr.filter((e, i) => i==0 || i==arr.length-1));

本文标签： javascriptGet first and last value from arrayStack Overflow