idea: browserslist for npm packages

The current implementation of browserslist good fit for applications, but is it a good fit for libraries?

I’m thinking out loud. https://github.com/ai/browserslist/issues/75 wants to add node.js support. Same time there is engines in package.json. Should engines directive allow to list browsers?

Like:

{
  "engines": {
    "Firefox": "> 20",
    "not ie": "<= 8"
  }
}

Can this information be used by browserslist to verify that all required packages met application browser requirements?

[michael-ciniawsky]

Unofficial, but the widely used package.browser (version of the package transpiled/written with changes for browser usage) property would also be nice to ‘support’ as mixture of package.engines && browserslist somehow 😃. Though this is not really browserslist issue 🙃

{
   name: "",
   version: "",
   module: 'path/to/esm.js', // (Source Code)
   // e.g babel-preset-env (targets via browerslist)
   main: 'path/to/cjs.js', // engines.node 
   browser: 'path/to/browser.js', // engines.browsers
   engines: {                                                                                        
     node: ">= 4",
     browsers: { 
        ...list
     }
  }
}

[jskrzypek]

The pkg.browser field should definitely be unofficially ‘specced’ by some entity and at best officially by npm

@michael-ciniawsky FWIW there’s already this: https://github.com/defunctzombie/package-browser-field-spec