function binarySearch(sortedArray, key){ let start = 0; let end = sortedArray.length - 1; while (start <= end) { let middle = Math.floor((start + end) / 2); if (sortedArray[middle] === key) { // found the key return middle; } else if (sortedArray[middle] < key) { // continue searching to the right start = middle + 1; } else { // search searching to the left end = middle - 1; } } // key wasn't found return -1; } var arr = [1,2,3,4,5,6,7,]; var key = 4; var res = binarySearch(arr,key); console.log("Element found at position " + res);