javascript - javascript - call math.rand, then scale and convert to int, in a function argumnet

Question

I need to perform the specified operations within the argumnts of a function. I saw this done once but I disremember the syntax.

Answer 1

Original answer see below for updated answer

...to perform the specified operations within the argumnts of a function...

I have no idea what "within" might mean there. :-)

But perhaps this is what you're looking for:

function foo(num) {
    return Math.round(Math.rand() * num);
}

More reading:

• MDN's pages on the Math object

---

Updated answer

Re your comment below:

I need the math to happen where it says "num" :).

You can't do that in JavaScript. When declaring a function, all you can put where I have num above is the names of formal arguments. You can't have expressions there.

You can do this, though:

function foo(num) {
    num = Math.round(Math.rand() * num);

    // ...and use `num`...
}

There's a very slight performance penalty for doing that rather than creating a new var within the function, e.g.:

function foo(n) {
    var num = Math.round(Math.rand() * n);

    // ...and use `num`...
}

...but it's very slight, likely to be washed out by whatever else you're doing.