If I have an array like. const arr = [1, 5, 7, 5, 13, 8, 1, 7, 3, 8, 5, 2, 1, 5, 7]; What would be the best way of finding that the array starts to repeat itself? In this instance that the first three numbers and the last three numbers are in a repeating pattern.

Mar 19, 2017 · The standard solution to find duplicates (in O (n) time) is to walk linearly through the list and add each item to a set. Each time, before doing so, check if it is already in the set. If it is, you've found a duplicate. if (seen.has(item)) { console.log(item + " is a duplicate"); } …

Dec 17, 2019 · I have been asked in the interview to find repetitive elements in array. I have found using for loop, but the interviewer asked for more improved way to find out, with effect to performance with out for loop .

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.

Aug 10, 2020 · There are a couple of ways to count duplicate elements in a javascript array. by using the forEach or for loop. Iterate over the array using a for loop.

Mar 8, 2024 · JavaScript allows us to find the repeating and missing number in a given array which includes numbers from 1 to N range. We are given an array that has numbers present from 1 to N range, where N is any natural number. One number is present two times and one number is missing from the range.

Jan 10, 2021 · To get our object to look like that, we introduce an if...else block. For each element in the array input, if the element is already a key in the object, we increment that key's value by one. If the element is not already in the object, we make …

To recognize a repeating pattern in an array using JavaScript, you can employ various techniques depending on the nature of the pattern you're looking for. Here's a general approach to get you started:

Mar 14, 2022 · Learn how to write a JavaScript program to efficiently find duplicate elements in an array. Discover tips, tricks, and code examples for quick implementation.

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