Reduce multiple ORs in IF statement in JavaScript

Question

Is there a simpler way to rewrite the following condition in JavaScript?

if ((x == 1) || (x == 3) || (x == 4) || (x == 17) || (x == 80)) {...}

Answer 1

This is a little function I found somewhere on the web:

function oc(a) {
    var o = {};
    for (var i = 0; i < a.length; i++) {
        o[a[i]] = '';
    }
    return o;
}

Used like this:

if (x in oc(1, 3, 4, 17, 80)) {...}

I'm using it for strings myself; haven't tried with numbers, but I guess it would work.