javascript - What is the (potential) drawback of using async functions everywhere?

Question

I am learning Javascript. This may sound like a crazy idea but I don't find clear answers on Google. Can I just replace all my regular functions/methods with async function everywhere? I mean there seems to be no downsides to this and it makes things so much simpler. Where the situation only involves synchronous steps, you just don't use await and it will work just like normal functions. Easy!

Personally I find having to distinguish async functions and normal functions unnecessarily burdensome. It's like driving a manual transmission car, where the car itself could easily handle the gearing by itself.

Am I missing something here?

Answer 1

async functions always return Promises. This means that anytime you're not dealing with something asynchronous, you would have to convert the returned Promise into a value before you could use it. For example:

const return4 = async () => 4;
console.log(4 + return4());