SOURCE

function binarySearch(arr,target){
    let left =0;
    let right = arr.length-1;
    while(left<=right){
        const mid = Math.floor((left+right)/2);

        if(arr[mid] === target){
            return mid;
        } else if(arr[mid] < target){
            left = mid+1
        } else {
            right = mid-1
        }
        return -1
    }
}

const arr = [1,3,5,7,9,11];
const target = 7;
const result = binarySearch(arr, target);

console.log(result)