JavaScript: Search JavaScript arrays with a binary search

JavaScript Function: Exercise-18 with Solution

Binary Search in Array

Write a function for searching JavaScript arrays with binary searches.

Note : A binary search searches by splitting an array into smaller and smaller chunks until it finds the desired value.

Visual Presentation:

Sample Solution-1:

JavaScript Code:

// Define a function named array_binary Search that performs binary search on a sorted array
function array_binarySearch(narray, delement) {
 // Calculate the middle position of the array
 var mposition = Math.floor(narray.length / 2);
 // Check if the middle element is equal to the desired element
 if (narray[mposition] === delement){
 return mposition;
 }
 // Check if the array has only one element and it is not equal to the desired element
 else if (narray.length === 1) 
 {
 // If true, return null as the element is not found
 return null;
 }
 // Check if the middle element is less than the desired element
 else if (narray[mposition] < delement) { // Create a new array containing elements to the right of the middle position var arr = narray.slice(mposition + 1); // Recursively call array_binarySearch on the new array var res = array_binarySearch(arr, delement); // Check if the result is null if (res === null) { // If true, return null return null; } else { // If false, return the adjusted index by adding mposition + 1 to the result return mposition + 1 + res; } } // If the middle element is greater than or equal to the desired element else { // Create a new array containing elements to the left of the middle position var arr1 = narray.slice(0, mposition); // Recursively call array_binarySearch on the new array return array_binarySearch(arr1, delement); } } // Create an example sorted array var myArray = [1, 2, 3, 5, 6, 7, 10, 11, 14, 15, 17, 19, 20, 22, 23]; // Log the result of calling array_binarySearch with the input array and desired element to the console console.log(array_binarySearch(myArray, 6)); 

Output:

4

Flowchart:

Live Demo:

See the Pen JavaScript - Search JavaScript arrays with a binary search-function-ex- 18 by w3resource (@w3resource) on CodePen.

Sample Solution-2:

JavaScript Code:

// Binary search function for sorted arrays
function binarySearch(arr, target) {
 let low = 0;
 let high = arr.length - 1;
 while (low <= high) { // Calculate the middle index const mid = Math.floor((low + high) / 2); // Check if the middle element is the target if (arr[mid] === target) { return mid; // Element found, return its index } else if (arr[mid] < target) { low = mid + 1; // If target is greater, search the right half } else { high = mid - 1; // If target is smaller, search the left half } } return -1; // Element not found } // Example usage: const sortedArray = [1, 2, 3, 5, 6, 7, 10, 11, 14, 15, 17, 19, 20, 22, 23]; const targetElement = 6; const resultIndex = binarySearch(sortedArray, targetElement); // Log the result to the console console.log(resultIndex); 

Output:

4

Flowchart:

For more Practice: Solve these Related Problems:

• Write a JavaScript function that implements binary search on a sorted array without using recursion.
• Write a JavaScript function that performs binary search recursively on a sorted array of numbers.
• Write a JavaScript function that executes binary search on an array of objects based on a specified key property.
• Write a JavaScript function that implements binary search and returns the index of the found element or -1 if not present.

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