convert decimal to hex missing padded 0

Question

I have this function here:

function d2h(d) { return (+d).toString(16); }

So say I put d2h(15);.

This will return f. I need it to return 0f.

Answer 1

Using String.padStart:

(d).toString(16).padStart(2, '0')

Answer 2

The most obvious way would be to check if it's only one character, and if so, add a zero before it:

function d2h(d) {
    var s = (+d).toString(16);
    if(s.length < 2) {
        s = '0' + s;
    }
    return s;
}

A less obvious way would be this:

function d2h(d) {
    return (d / 256 + 1 / 512).toString(16).substring(2, 4);
}

But that's too tricky; I'd definitely stick with the first solution.