Binary Search In JavaScript Last Updated : 10 Jan, 2025 Summarize Suggest changes Share Like Article Like Report Binary Search is a searching technique that works on the Divide and Conquer approach. It is used to search for any element in a sorted array. Compared with linear, binary search is much faster with a Time Complexity of O(logN), whereas linear search works in O(N) time complexityExamples: Input : arr[] = {1, 3, 5, 7, 8, 9}, x = 5Output : Element found!Input : arr[] = {1, 3, 5, 7, 8, 9}, x = 6Output : Element not found!Note: Assuming the array is sorted.These are the following ways to do Binary Search in JavaScript: Table of ContentRecursive ApproachIterative ApproachRecursive ApproachBASE CONDITION: If the starting index is greater than the ending index return false.Compute the middle index.Compare the middle element with the number x. If equal return true.If greater, call the same function with ending index = middle-1 and repeat step 1.If smaller, call the same function with starting index = middle+1 and repeat step 1. Example: This example shows the use of the above-explained approach. javascript let recursiveFunction = function (arr, x, start, end) { // Base Condition if (start > end) return false; // Find the middle index let mid = Math.floor((start + end) / 2); // Compare mid with given key x if (arr[mid] === x) return true; // If element at mid is greater than x, // search in the left half of mid if (arr[mid] > x) return recursiveFunction(arr, x, start, mid - 1); else // If element at mid is smaller than x, // search in the right half of mid return recursiveFunction(arr, x, mid + 1, end); } // Driver code let arr = [1, 3, 5, 7, 8, 9]; let x = 5; if (recursiveFunction(arr, x, 0, arr.length - 1)) { console.log("Element found!"); } else { console.log("Element not found!"); } x = 6; if (recursiveFunction(arr, x, 0, arr.length - 1)) { console.log("Element found!"); } else { console.log("Element not found!"); } OutputElement found! Element not found! Time Complexity: O(logN)Auxiliary Space: O(1) Iterative ApproachIn this iterative approach, instead of recursion, we use a while loop, and the loop runs until it hits the base condition, i.e. start becomes greater than end. Example: This example shows the use of the above-explained approach. javascript // Iterative function to implement Binary Search let iterativeFunction = function (arr, x) { let start = 0, end = arr.length - 1; // Iterate while start not meets end while (start <= end) { // Find the mid index let mid = Math.floor((start + end) / 2); // If element is present at // mid, return True if (arr[mid] === x) return true; // Else look in left or // right half accordingly else if (arr[mid] < x) start = mid + 1; else end = mid - 1; } return false; } // Driver code let arr = [1, 3, 5, 7, 8, 9]; let x = 5; if (iterativeFunction(arr, x, 0, arr.length - 1)) { console.log("Element found!"); } else { console.log("Element not found!"); } x = 8; if (iterativeFunction(arr, x, 0, arr.length - 1)) { console.log("Element found!"); } else { console.log("Element not found!"); } OutputElement found! Element found! Time Complexity: O(logN).Auxiliary Space: O(1) Advertise with us Next Article JavaScript Program to Find Index of First Occurrence of Target Element in Sorted Array I imdhruvgupta Follow Similar Reads Learn Data Structures with Javascript | DSA using JavaScript Tutorial JavaScript (JS) is the most popular lightweight, interpreted programming language, and might be your first preference for Client-side as well as Server-side developments. But have you thought about using JavaScript for DSA? Learning Data Structures and Algorithms can be difficult when combined with 7 min read Learn Algorithms with Javascript | DSA using JavaScript Tutorial This Algorithms with Javascript tutorial is designed to help you understand and implement fundamental algorithms using the versatile JavaScript programming language. 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Below are the approaches to reverse a lin 3 min read Article Tags : JavaScript Technical Scripter 2018 Binary Search Practice Tags : Binary Search Like