JuniorTheoryCommon

What does the program print?

JavaScript

function add(a, b) {
    return a + b;
}

console.log(add(1), add(1, 2, 3));

NaN 3

Expecting a missing argument to count as 0: the parameter b is undefined, and 1 + undefined is NaN, so add(1) prints NaN.
Expecting the extra argument 3 to be added too: add has only two parameters, so the third argument is ignored and add(1, 2, 3) is 3.

JuniorTheoryCommon

JavaScript

function add(a, b) {
    return a + b;
}

console.log(add(1), add(1, 2, 3));

NaN 3

Expecting a missing argument to count as 0: the parameter b is undefined, and 1 + undefined is NaN, so add(1) prints NaN.
Expecting the extra argument 3 to be added too: add has only two parameters, so the third argument is ignored and add(1, 2, 3) is 3.