New Rule: no-top-level-await

[DMartens]

Rule details

It would warn about using top-level awaits as it conflicts with require(esm).
Unfortunately no-restricted-syntax cannot be used as the following should be ignored:

• files with a shebang or without exports
• files called from package.json scripts

What type of rule is this?

Warns about a potential problem

Example code

await fn();

for await (const x of asyncGenerator()) {
}

Participation

• I am willing to submit a pull request to implement this rule.

Additional comments

This rule was discussed in the eslint repo but declined with a reference to open here.

[scagood]

I like this idea, I think it'd be best to keep it reasonably simple at the start though (eg detecting cjs/esm and erroring only for cjs)

ignores is always a nice option to have :)

[voxpelli]

It's in ESM files it should error, as any ESM file with a top level await can't be used with the new ESM-support in require() 🙂

Maybe there should be an (optional) exception for CLI-scripts, as they will never be used with require() and top level await is quite helpful in those