Remove the Last 2 Elements from an Array in JavaScript

Remove the Last 2 Elements from an Array #

Use the splice() method to remove the last 2 elements from an array, e.g. arr.splice(arr.length - 2, 2). The splice method will delete the 2 last elements from the array and return a new array containing the deleted elements.

index.js

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// 👇️ With mutation
const arr1 = ['one', 'two', 'three', 'four'];

arr1.splice(arr1.length - 2, 2);
console.log(arr1); // 👉️ ['one', 'two']

We used the Array.splice method to delete the last 2 elements from an array.

These are the 2 arguments we passed to the method:

start index - the index at which to start changing the array
delete count - how many elements we want to delete from the array

Indexes are zero-based in JavaScript, meaning the first element in an array has an index of 0, and the last an index of array.length - 1.

We used the array's length to calculate the start index. Our array has a length of 4, so by subtracting 2 from it, the splice method starts changing the array at index 2 (the third array element).

We removed 2 items, by setting the delete count parameter to 2.

Note that the splice method changes the contents of the original array. If you want to get a new array without the last 2 elements of the original array, you can use the slice method instead.

To remove the last 2 elements from an array, call the slice() method, passing it 0 and -2 as parameters. The slice method will return a new array containing the portion of the original array, without the last 2 elements.

index.js

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// 👇️ Without mutations

const arr2 = ['one', 'two', 'three', 'four'];

const newArr = arr2.slice(0, -2);
console.log(newArr); // 👉️ ['one', 'two']

console.log(arr2); // 👉️ ['one', 'two', 'three', 'four']

We passed the following parameters to the Array.slice method:

start index - the index of the first element to be included in the new array
end index - extract elements up to, but not including this index. A negative index of -2 means go up to, but not including the last 2 elements of the array

Passing an end index parameter of -2 and array.length - 2 is the same. We instruct the slice method to go up to, but not including the last 2 elements in the array.

The slice method does not mutate the original array, instead it returns a new array.

Using the slice method is my preferred approach because in my experience, mutations are very difficult to track throughout a code base, especially when changing the same array / object in different places.

Remove the Last 2 Elements from an Array in JavaScript

Remove the Last 2 Elements from an Array #

Further Reading #

Borislav Hadzhiev