JS Object Defaults 1

gistfile1.js

function setBG (options) {
    var args = {
        red: 255,
        green: 255,
        blue: 255
    }

    // overwrite defaults
    for (var i in options) {
        args[i] = options[i];
    }

    document.body.style.backgroundColor = "rgb(" + args.red + "," + args.green + "," + args.blue + ")";
}

setBG({red: 128, blue: 100});