Slice in JavaScript

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

Syntax:

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 😜, lets understand by few examples.

Using two arguments ✅:

const arr = ['🍏', '🍓', '🌽', '🍇', '🍒'];
const newArr = arr.slice(2,4);
console.log(newArr); // ["🌽", "🍇"]

Without arguments, you get a copy of the full array ✅

const arr = ['🍏', '🍓', '🌽', '🍇', '🍒'];
const newArr = arr.slice();
console.log(newArr); // ["🍏", "🍓", "🌽", "🍇", "🍒"]

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

const arr = ['🍏', '🍓', '🌽', '🍇', '🍒'];
const newArr = arr.slice(3);
console.log(newArr); // ["🍇", "🍒"]

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

const arr = ['🍏', '🍓', '🌽', '🍇', '🍒'];
const newArr = arr.slice(2,-2);
console.log(newArr); // ["🌽"]

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

const arr = ['🍏', '🍓', '🌽', '🍇', '🍒'];
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 ✅

const arr = ['🍏', '🍓', '🌽', '🍇', '🍒'];
const newArr = arr.slice(1,9);
console.log(newArr); // ["🍓", "🌽", "🍇", "🍒"]

slice() method can also be used for strings ✅

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

Note: 🧨

Slice is immutable and Splice mutates the array.

Reference 🧐

Slice MDN

🌟 Twitter

👩🏻‍💻 Suprabha.me

🌟 Instagram

Comments

[Functional Javascript]

Nice refresher Suprabha.

Here are two lists that people may find useful:

mutator array methods:

push (back add)
pop (back remove)
unshift (front add)
shift (front remove)
splice
sort
reverse
fill
forEach

non-mutator array methods:

concat
join
filter
slice
map
reduce
find
findIndex
some
every
includes
flat
flatMap

[Suprabha]

Hahaha I can understand. I fixed that 🤪

[Ashutosh]

Very nicely explained

[Suprabha]

I tried to join, but wouldn't able to join to the group.