takes a function and returns a function that will only be applied if it has arguments that aren't null or undefined

maybe.js

function maybe(fn) {
    return function () {
        var args = Array.prototype.slice.call(arguments);
        if (!args.length) {
            return;
        }
        for (var index = 0, length = args.length; index < length; index += 1) {
            if (args[index] == null) {
                return;
            }
        }
        return fn.apply(this, args);
    }
}

// usage
var a = maybe(alert);
a(null); // doesn't call the original (alert) function
a('howdy'); // alerts 'howdy'

var plus = maybe(sum);
a(plus(3, 4)); // alerts 7
a(plus(3, null)); // plus returns early and a returns early (neither sum or alert are called)

function sum(x, y) {
    return x + y;
}