Spread Operator in JavaScript

Uifoxes — Sat, 24 Jul 2021 11:58:03 +0000

What is spread operator in Javascript ?
Spread Operator allows you to spread out the elements of an iterable object such as Array.

Syntax : [ ... Array ]

When to use spread operator ?
Suppose you have a array and you want to clone it.

let x = [1,2,3,4,5];
let y = x;
The above code is not cloning , x sets a reference to y , if the value of x gets changed the the value of y will also get changed.

There are many ways to can clone array in javascript

let x = [1,2,3,4,5];
let y = Object.assign([],x);

console.log(y);

//Output : [1,2,3,4,5]

Source : https://codelearningpoint.com/

Remove duplicates from array in javascript

Uifoxes — Sat, 24 Jul 2021 11:56:46 +0000

You can use filter() method to remove duplicates from array , if the index of the element gets matched with the indexOf value then only that element will get added.

let data = [1, 2, 3, 2, 1];

let uniqueData = data.filter((c, index) => {
return data.indexOf(c) == index;
});

console.log(uniqueData);

Output - [ 1, 2, 3 ]

Source : https://codelearningpoint.com/

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Spread Operator in JavaScript

Remove duplicates from array in javascript