Return in JavaScript revisited

Yesterday, we looked at return in JavaScript.

I got some great responses from readers, and thought it was worth sharing a few of them here.

Line breaks

If you put a line break after your return without starting a value to return, JavaScript will interpret it as being complete (because semicolons are optional, ick) and return null.

// returns null
var hiThere = function (name) {
	return
		'Hello ' + name;
};

As long as you start your value, you can include line breaks.

// returns "Hello {name}"
var hiThere = function (name) {
	return 'Hello ' +
		name;
};

Implied return

Steve Griffith runs a fantastic YouTube channel on front end development.

He wrote back reminding me that JavaScript functions have an implied return when you provide one or not.

Take this function, that returns true if num is bigger than 10, and otherwise returns false.

var isItBiggerThanTen = function (num) {
	if (num > 10) {
		return true;
	}
	return false;
};

If you do not return anything, a function will return undefined, which validates as falsey.

var isItBiggerThanTen = function (num) {
	if (num > 10) {
		return true;
	}
};

In chatting about this with me, Steve realized he didn’t actually have a video explaining this yet, so he put one together for me. Thanks Steve!

Hope that clears some things up.