What is the spread operator in javascript?

The spread operator in JavaScript is useful for adding elements to an array, combining arrays and more!

Here’s an example:

let arr1 = [1,2,3];
let arr2 = [4,5];
let arr3 = […arr1,…arr2];
console.log(arr3);
// Output: [ 1, 2, 3, 4, …


This content originally appeared on DEV Community and was authored by Code_Jedi

The spread operator in JavaScript is useful for adding elements to an array, combining arrays and more!

Here's an example:

let arr1 = [1,2,3]; 
let arr2 = [4,5]; 
let arr3 = [...arr1,...arr2]; 
console.log(arr3);
// Output: [ 1, 2, 3, 4, 5 ]

As you can see the spread operator(represented as "...") was able to combine "arr1" and "arr2" into "arr3".

The spread operator can also expand arrays:

let arr = ["a","b"]; 
let arr2 = [...arr,"c","d"]; 
console.log(arr2); 
// Output: ["a", "b", "c", "d"]

As you can see, the spread operator here was able to add elements "c" and "d" to "arr", thus creating a bigger array.

But that's not all!

The spread operator can also merge objects:

const Person = { 
    name: "Bob", 
    age: 45,
}; 
const ExtraInfo = { 
    country: "Belgium", 
    city: "Brussels", 
}; 
const user = {... Person, ... ExtraInfo};
// Output: {  name: "Bob",  age: 45, country: "Belgium", city: "Brussels" }

There it is, the javascript spread operator.

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This content originally appeared on DEV Community and was authored by Code_Jedi


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