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 = 5// Initial empty arrayconst arr = [];// Null checkif (n == 0) { console.log(null)}do { // Generating random number const randomNumber = Math .floor(Math.random() * 100) + 1 // Pushing into the array only // if the array does not contain it if (!arr.includes(randomNumber)) { arr.push(randomNumber); }} while (arr.length < n);// Printing the array elementsconsole.log(arr) |
Output
[ 29, 36, 38, 83, 50 ]
Time complexity:
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 = 5// Initial empty arrayconst arr = [];// Null Checkif (n == 0) { console.log(null)}let randomnumbers = new Set, ans;// We keep adding elements till// size of set is equal to n while (randomnumbers.size < n) { // Generating random number // and adding it randomnumbers.add(Math.floor( Math.random() * 100) + 1);}// Copying set elements into // the result arrayans = [...randomnumbers];// Printing the arrayconsole.log(ans) |
Output
[ 41, 75, 57, 62, 92 ]
Time complexity:
O(n)
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