In this article, we will learn how to create an array containing non-repeating elements in JavaScript.
The following are the two approaches to generate an array containing n number of non-repeating random numbers.
- Using do-while loop and includes() Method.
- Using a set and checking its size
Method 1: Using do-while loop and includes() Method
Here, the includes() function checks if an element is present in the array or not.
Example:
JavaScript
// You can take this value from userconst n = 5Â
// Initial empty arrayconst arr = [];Â
// Null checkif (n == 0) {Â Â Â Â console.log(null)}Â
do {    // Generating random number    const randomNumber = Math        .floor(Math.random() * 100) + 1Â
    // Pushing into the array only     // if the array does not contain it    if (!arr.includes(randomNumber)) {        arr.push(randomNumber);    }} while (arr.length < n);Â
// Printing the array elementsconsole.log(arr) |
Output
[ 29, 36, 38, 83, 50 ]
Time complexity:Â
O(n2)
Method 2: Using a set and checking its size
Remember that a set does not allow duplicate elements.
Example:
JavaScript
// You can take this value from userconst n = 5Â
// Initial empty arrayconst arr = [];Â
// Null Checkif (n == 0) {Â Â Â Â console.log(null)}Â
let randomnumbers = new Set, ans;Â
// We keep adding elements till// size of set is equal to n while (randomnumbers.size < n) {Â
    // Generating random number     // and adding it    randomnumbers.add(Math.floor(        Math.random() * 100) + 1);}Â
// Copying set elements into // the result arrayans = [...randomnumbers];Â
// Printing the arrayconsole.log(ans) |
Output
[ 41, 75, 57, 62, 92 ]
Time complexity:
O(n)
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