using `return` in the top level of a node.js script

[75lb]

using standard v7, trying to validate this node.js script:

console.log('one')
return 
console.log('two')

throws this issue:

Parsing error: 'return' outside of function

In node.js, the top level script is wrapped by a function. Even though it might look like use of return outside a function, it is not..

what to do here? This is a valid use of return..

[LinusU]

I thought that this had been the case for a long time. I would recommend using process.exit(0) instead.

[75lb]

@LinusU if return and process.exit() were equivalent, i would.. they are not related and have different consequences.

[feross]

Yes, this has been an issue for a long time.

This is an unfortunate side effect of two bad decisions made by TC39:

1. Top-level return is an error.
2. ES modules have a completely different parsing mode ("module") than the normal mode ("script").

The decision to have two modes means that every piece of tooling that parses JS has to expose this decision to the user.

To keep standard simple, we just assume "module" which makes the ESLint parser support all the module syntax (export, etc.) but has the downside of preventing top-level return. :(

If we assumed "script" then many more things would not work, so this is the right compromise I think.

[75lb]

could you leave the "module" or "script" mode decision to the user with a --mode option or similar?

The current behaviour prevents me using Standard in test suites or CI as it will always fail when linting my top-level scripts (which typically contain return in a catch handler to gracefully exit the process).

[feross]

It's an intentional decision to not have modes or options in standard. I understand that this is painful right now, but adding a mode would add complexity for every user of standard, in perpetuity.

We'll have to find a better long-term workaround for this.

For now, consider not linting the files which contain top-level return.