How to copy an array in Javascript

In this tutorial, we are going to see how to copy an array in Javascript. There are two types of copies that can be made on an array.

• Simple copy
• Deep copy

 

Simple copy

Arrays in javascript are just objects with properties and methods. When we directly assign an array to another variable, it is copied superficially.

This means that it only references the array, it does not copy all the elements.
 
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Example:

var arr1 = [1, 2, 3, 4];

//simple copy
var arr2 = arr1;   
console.log(arr2); //[1, 2, 3, 4];

//Update the original array
arr1.push(5); //[1, 2, 3, 4, 5]

//The update is reflected in the copied array
console.log(arr2);  //[1, 2, 3, 4, 5]

 

Deep copy

We can concatenate the original array with an empty array and return it to create a deep copy.

var arr1 = [1, 2, 3, 4];

//Deep copy
var arr2 = [].concat(tab1);  
console.log(arr2); //[1, 2, 3, 4];

//Update the original array
arr1.push(5); //[1, 2, 3, 4, 5]

//The update is not reflected in the copied array
console.log(arr2);  //[1, 2, 3, 4]

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