It’s certainly doable. The `defaultValue` parameter is passed by value, so it will never be rebound. The result of using `typeof` on a value never changes in JS

It’s certainly doable. The `defaultValue` parameter is passed by value, so it will never be rebound. The result of using `typeof` on a value never changes in JS, even if the value is modified. So... it should be possible to optimize the check away after the first time.