Don't abuse `return`

to_return_or_not_return.js

// BAD: `return` shouldn't be used to control flow/execution
function loadProductData(query) {
	if ($('body').hasClass('busy'))
		return;

	$.ajax( /*...*/ );
}

// GREAT SUCCESS: Just do this instead (OMG duh!)
function loadProductData(query) {
	if (!$('body').hasClass('busy')) {
		$.ajax( /*...*/ );
	}
}

// BAD: Always return if you're going to return
function performScientificMaths(x, y) {
	if (x + y > 0) {
		return x + y;
	}
}

// GREATE SUCCESS: Never a null (I mean, undefined) moment
function performScientificMaths(x, y) {
	if (x + y > 0) {
		return x + y;
	} else {
		return null;
	}
}

And I guess in the, albeit rare, case a function is refactored to start actually returning useful values, you're not unexpectedly returning undefined.

Am I grasping at straws yet?