Javascript Semi-Signficant Figures

gistfile1.js

/**

Handy function to get (kind of) significant figures from Javascript numbers.
Unlike built-in Javascript methods, this works for all numbers, not just decimals.

Example: sigFigs(12345, 2) -> 12000
         sigFigs(0.022, 1) -> 0.02
**/

function sigFigs(num, figures) {
    var delta = Math.pow(10, Math.ceil(Math.log(num) / Math.log(10)) - figures);

    return Math.round(num / delta) * delta;
}

I don't know why you would have to calculate something like this manually, but no problem! :D