JavaScript - shorten math function

Question

function randomize() {
var ra = Math.floor(Math.random()*ar.length=4);
document.getElementById('es').innerHTML = ar[ra];
}

Is there a way to short this code even more than it is? The reason why is because I'm going to be using this code a lot in other projects and objects and I cannot just call it inside like this: randomize(); because I have diffrent arrays.

Answer 1

function randomize() {document.getElementById('es').innerHTML = ar[Math.floor(Math.random()*ar.length)];}

But you wanted to use it more without a function call:

function $(id) {
return document.getElementById(id);
}

function randomize() {
$('es').innerHTML = ar[Math.floor(Math.random()*ar.length)];
}

And instead of Math.floor , you can use ~~ for a microscopical faster diffrence.

This saves some space and time if you are going to use it more. But if only one time, use the first example.

Answer 2

Without knowing what, precisely, you're doing, I'd suggest passing the relevant arguments into the function as parameters:

function randomize(el, array){
    if (!el || !array){
        return false;
    }
    else {
        var ra = Math.floor(Math.random() * array.length=4);
        // please note that I don't understand what's happening in the above line
        // and suspect, quite strongly, that the '=4' was a typo. Correct as necessary
        el.innerHTML = ar[ra];
    }
}

// call:
randomize(document.getElementById('es'), ['1','2']);
/* or:
var el = document.getElementById('es'),
    array = ['one','two'];
randomize(el,array);