Throwing strings instead of Errors

Question

Since we can throw anything with the throw keyword in Javascript, can't we just throw an error message string directly?

Does anyone know any catch in this?

Let me add some background to this: Very often, in the JavaScript world, people rely on parameter checking as opposed to using the try-catch mechanism, so it makes sense to only throw fatal errors with throw. Still, to be able to catch some system Errors, I have to use a different class for my own errors and instead of creating a subclass of Error, I think I should just use String.

Answer 1

While it is okay possible to throw any value, it is generally considered poor form to throw anything other than an instance of Error or one of its subclasses. There are several reasons for this:

1. Catching code may expect the thrown object to have the usual message, stacktrace, and name properties that appear on Errors.
2. Lack of a stacktrace makes debugging problematic, especially in the case of uncaught exceptions / unhandled rejections. E.g. Debugging an "Uncaught [Object object]" error can be particularly painful.

Answer 2

Yes, you can throw other values, but it's not a good practice.

Does anyone know any catch in this?

A string is not an error object, and does not convey any useful debugging information. Devtools rely on that, such as the file and line where the error was created, the stacktrace at the throw location etc, which are available as properties on Error objects.

Whenever you think of throwing a primitive string value, throw a new Error("<the string>") instead.