顺序查找

function seqSearch(arr, data) {
    for (var i = 0; i < arr.length; ++i) {
        if (arr[i] == data) {
            return true;
        }
    }
    return false;
}

二分查找（ 只对有序的）

function binSearch(arr, data) {
    var upperBound = arr.length - 1,
        lowerBound = 0;
    while (lowerBound < upperBound) {
        var mid = math.floor((lowerBound + upperBound) / 2);
        if (data < arr[mid]) {
            upperBound = mid - 1;
        } else if (data > arr[mid]) {
            lowerBound = mid + 1;
        } else {
            return mid;
        }
    }
    return -1;
}