二分查找算法的 JavaScript 实现

var arr = [0, 2, 4, 27, 28, 54, 67, 74, 75, 79, 86, 97, 289, 290, 678]

function binarySearch(arr, val) {
    var start = 0, end = arr.length - 1;
    while (start <= end) {
        var mid = Math.floor((start + end) / 2);
        if (arr[mid] > val) {
            end = mid - 1;
        } else if (arr[mid] < val) {
            start = mid + 1;
        } else {
            return mid;
        }
    }
}

console.log(binarySearch(arr, 75)); // 8