Truncate an Array in JavaScript

In this article, we will learn how to truncate an array in JavaScript by reducing its length and keeping only the required elements.

Approach 1: Using length Property

The length property can be directly modified to reduce the size of an array. Setting it to a smaller value removes all elements beyond the specified length.

Example: In this example, we truncate the array to its first three elements by changing its length property.

const arr = [1, 2, 3, 4, 5, 6];

arr.length = 3;

console.log(arr);

[ 1, 2, 3 ]

Approach 2: Using splice() Method

The splice() method can remove all elements from a specified index to the end of an array. It modifies the original array.

Example: In this example, we remove all elements starting from index 4.

const arr = [1, 2, 3, 4, 5, 6];

arr.splice(4);

console.log(arr);

[ 1, 2, 3, 4 ]

Approach 3: Using slice() Method

The slice() method creates a new array containing elements from the specified range. Unlike splice(), it does not modify the original array.

Example: In this example, we use slice() to keep only the first two elements.

const arr = ["Geeks", "Geek", "GFG", "gfg", "G"];

const result = arr.slice(0, 2);

console.log(result);

[ 'Geeks', 'Geek' ]

Approach 4: Using pop() in a Loop

The pop() method removes the last element from an array. By calling it repeatedly, we can remove elements until the array reaches the desired length.

Example: In this example, we remove elements from the end until the array contains three elements.

const arr = [1, 2, 3, 4, 5];
const len = 3;

while (arr.length > len) {
    arr.pop();
}

console.log(arr);

[ 1, 2, 3 ]

Output

GeeksforGeeks is a computer...

Approach 5: Using filter() Method

The filter() method creates a new array containing elements that satisfy a condition. By checking the index, we can keep only the required number of elements.

Example: In this example, we use filter() to keep the first three elements of the array.

const arr = [1, 2, 3, 4, 5, 6];

const result = arr.filter((element, index) => index < 3);

console.log(result);