binarySearch.js

// A function that takes 2 arguments: an array and a value to search in the array

function binarySearch(arr, target) {

    // make a copy of the array and sort it so that we can perform binary search
    const sortedArray = [...arr];
    sortedArray.sort();
    let mid;
    let start = 0;
    let end = arr.length - 1;
    while (start <= end) {
        mid = Math.floor((start + end) / 2);
        if (sortedArray[mid] === target) {

            // get the position of target in the original array
            return arr.indexOf(sortedArray[mid]);
        }
        if (sortedArray[mid] > target) {
            end = mid - 1;
        }
        if (sortedArray[mid] < target) {
            start = mid + 1;
        }
    }
    return -1;
}

console.log(binarySearch([5, 6, 7, 7, 4, 8], 100))
console.log(binarySearch([5, 6, 7, 7, 4, 8], 7))
console.log(binarySearch([5, 6, 7, 7, 4, 8], 1))