SOURCE

//两个数相加
function cool(num1, num2) {
    console.log(num1 + num2)
}
cool(1, 3);
cool(1, 6);


//两个数之间的和
function coolS(start, end) {
    var sum = 0;
    for (var i = start; i <= end; i++) {
        sum += i;
    } console.log(sum);
}

coolS(1, 3);
coolS(1, 10);