Sep 2, 2015 · You could use SET to remove duplicates and compare, If you copy the array into a set it will remove any duplicates. Then simply compare the length of the array to the size of the set. function hasDuplicates(a) { const noDups = new Set(a); return a.length !== noDups.size; }

Jul 9, 2016 · Interestingly the most obvious and elegant solution (imho) is missing: Array.prototype.reduce (...). All major browsers support this feature since about 2011 (IE) or even earlier (all others): prev[cur] = (prev[cur] || 0) + 1; return prev; EDIT: By using the comma operator in an arrow function, we can write it in one single line of code:

JavaScript : Remove all duplicate elements from the internal arrays of the given 2-D array

Apr 7, 2025 · In JavaScript, array methods such as filter () and indexOf () can be used to find duplicates in a concise way. filter () creates a new array containing elements that satisfy a condition. arr.indexOf (value) returns the first occurrence index of value.

Mar 14, 2022 · To find duplicates in an array using JavaScript, combining the filter and indexOf methods provides an elegant solution. The filter method creates a new array with all elements that pass the test implemented by the provided function.

Learn how to find duplicate values in a JavaScript array with this comprehensive guide, including examples and step-by-step instructions.

We are required to write a JavaScript function that takes in a two-dimensional array of literals. Our function should return a new array that contains all the entries from the original array but the repeating ones. The code for this will be −. [1,2,3,4,5], [3,4,6,7,8,2], [7,2,4,9,11,15], [10,12,3,7,11] let map = {}; let res = [];

Jul 3, 2021 · Learn how to check if an array contains duplicate values using indexOf (), set object, and iteration in JavaScript.

May 4, 2023 · In this article, let’s look at the different ways to find duplicates in an array in JavaScript. We’re going to be looking at different pre-defined JavaScript methods and finally some manual methods of finding the duplicates (usually using loops).

Feb 27, 2025 · javascript 1. Using a Set for Efficient Duplicate Detection. JavaScript’s Set object is perfect for detecting duplicates because it stores only unique values. By iterating over the array...