Throw errors on wrong feature and region names from Can I Use

[sashachabin]

Problem

Recently I made mistakes in queries that use caniuse-lite data. It's regional usage statistics query >0% in [Region] and feature support query supports [feature-name] .

Browserslist crashes and doesn't output errors to the user. It seems that the Browserslist, as in other cases, should indicate user errors (especially if the request consists of several parts).

Other discussions about one of these problems: #684, PSPDFKit-labs/browserslist.dev#39

Bad requests examples

Supports

'supports replace-all' — example from Issue #684

Error message

➜  ~ npx browserslist 'supports replace-all'
/usr/local/lib/node_modules/browserslist/cli.js:96
      throw e
      ^

Error: Cannot find module 'caniuse-lite/data/features/replace-all.js'

Region

'>2% in __' — 2 wrong symbols

Error message

➜  ~ npx browserslist '>2% in __' 
/usr/local/lib/node_modules/browserslist/cli.js:96
      throw e
      ^

Error: Cannot find module 'caniuse-lite/data/regions/__.js'

'>2% in alt-__' — 2 wrong symbols after alt-

Error message

➜  ~ npx browserslist '>2% in alt-__'
/usr/local/lib/node_modules/browserslist/cli.js:96
      throw e
      ^

Error: Cannot find module 'caniuse-lite/data/regions/alt-__.js'

My suggestions

• Wrap dynamic require('caniuse-lite/**/*.js') with try { ... } catch { throw new BrowserslistError('...') } with messages:
  • Unknown feature name ${name}
  • Unknown region name ${name} — for countries and continents
• Add tests

Result

➜  ~ npx browserslist '>0% in LL'
browserslist: Unknown region name `LL`.

[ai]

Looks very good

[ai]

Thanks. Released in 4.21.3.