Slice in JavaScript

Slice method returns a new array with a copied slice from the original array.


arr.slice([start[, end]])

start refers Zero-based index. If start is undefined, slice starts from the index 0.

In end, slice extracts up to but not including end.

Its too theoretically right ๐Ÿ˜œ, lets understand by few examples.

Using two arguments โœ…:

const arr = ['๐Ÿ', '๐Ÿ“', '๐ŸŒฝ', '๐Ÿ‡', '๐Ÿ’'];
const newArr = arr.slice(2,4);
console.log(newArr); // ["๐ŸŒฝ", "๐Ÿ‡"]

Without arguments, you get a copy of the full array โœ…

const arr = ['๐Ÿ', '๐Ÿ“', '๐ŸŒฝ', '๐Ÿ‡', '๐Ÿ’'];
const newArr = arr.slice();
console.log(newArr); // ["๐Ÿ", "๐Ÿ“", "๐ŸŒฝ", "๐Ÿ‡", "๐Ÿ’"]

Using one argument, you get a copy from the specified index to the end of the array โœ…

const arr = ['๐Ÿ', '๐Ÿ“', '๐ŸŒฝ', '๐Ÿ‡', '๐Ÿ’'];
const newArr = arr.slice(3);
console.log(newArr); // ["๐Ÿ‡", "๐Ÿ’"]

Index can also be negative, in which case the starting index is calculated from the end โœ…

const arr = ['๐Ÿ', '๐Ÿ“', '๐ŸŒฝ', '๐Ÿ‡', '๐Ÿ’'];
const newArr = arr.slice(2,-2);
console.log(newArr); // ["๐ŸŒฝ"]

If start is greater than the index range of the sequence, an empty array is returned โœ…

const arr = ['๐Ÿ', '๐Ÿ“', '๐ŸŒฝ', '๐Ÿ‡', '๐Ÿ’'];
const newArr = arr.slice(6);
console.log(newArr); // []

If end is greater than the length of the sequence, slice extracts through to the end of the sequence โœ…

const arr = ['๐Ÿ', '๐Ÿ“', '๐ŸŒฝ', '๐Ÿ‡', '๐Ÿ’'];
const newArr = arr.slice(1,9);
console.log(newArr); // ["๐Ÿ“", "๐ŸŒฝ", "๐Ÿ‡", "๐Ÿ’"]

slice() method can also be used for strings โœ…

const arr = 'suprabha';
const newArr = arr.slice(0,3);
console.log(newArr); // "sup"

Note: ๐Ÿงจ

Slice is immutable and Splice mutates the array.

Reference ๐Ÿง

Slice MDN