Quick feature checking in JS

'example' in navigator; // => false

Make it a function:

function exampleExists() {
    return 'example' in navigator;
}

exampleExists(); // => false

How about reusable?

function featureExists(feature) {
    return feature in navigator;
}

Not much more to it than that. Comes in handy when depending on Modernizr might be a bit too much.