docs: Fix example in README

[AdnoC]

Example didn't account for axe-puppeteer exporting multiple things. Also added comments about the context of the example code. Seems like export default stopped working at some point, since I know the code used to work.

Closes issue:

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[stephenmathieson]

It would probably be best to just put this code in an async fn so that people can copy/paste and run without modifying anything.

What do you think?

[stephenmathieson]

It'd be nice if this wasn't required. Can we just do module.exports = AxePuppeteer instead? I know TS will complain, but we can just disable the linter for the added line.

[AdnoC]

The problem is that then we can't export anything else

[AdnoC]

Which means no access to the loadPage function.

[stephenmathieson]

Can we do something like:

// The below is to ensure CommonJS `require()` works as expected.
// tslint:disable-next-line
exports = module.exports = AxePuppeteer

// ESM exports.
export { loadPage }
export default AxePuppeteer

Note that I haven't tested this.

[AdnoC]

Nope. loadPage is undefined with that. Apparently CommonJS doesn't explicitly have "default" as a thing.

CommonJS modules only have a default export. exports.var2 = is not a var2 export, it is the var2 property of the default export.

Modules allow for a single default export to be defined alongside any number of named exports. Node’s CJS implementation sort of allows for doing one or the other of these, but not both. You can either export a single value, or an object with a bunch of keyed values.

With default there is horrible experience for commonJS users who have to const {default} = require('module/foo'); instead of const {Foo} = require('module/foo'). You will most likely want to rename the default export to something else when you import it.

[stephenmathieson]

I did a bit of testing and this will work fine. See this TypeScript playground example for proof.

Note that module.exports and exports.default are set there, as well as exports.loadPage.

[stephenmathieson]

Ahh, I see, exports is overwritten after we set exports.loadPage. Disregard :)