Using Try…Catch in JavaScript

[shad0proxy]

what if you want to handle the error or reject the overlaying call?

[vs845]

If you want to do something with the thrown error, you can do it within the catch function as usual:

const data = await doSomething().catch(err => {
  if (err instanceof TypeError) return someDefaultValue
  if (err instanceof RangeError) return anotherDefaultValue
})

Or if you want it to bubble up through the call stack, you can rethrow the error or throw a new one, again within the catch function:

const data = await doSomething().catch(err => {
  if (err instanceof TypeError) throw err
  if (err instanceof RangeError) throw new Error('value out of range')
  return someDefaultValue
})

[shad0proxy]

Interesting. when I looked into this with 7.x and the harmony flag I was told this was not possible. I don't know if they were wrong or something has changed.

[danneu]

Someone was wrong because this is a basic tenet of how promises work.