Better explain Babel config browsersListEnv

alphagov · Jul 14, 2023 · bb9e80f · bb9e80f
1 parent 7e412fe
commit bb9e80f
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Showing 2 changed files with 16 additions and 12 deletions.
diff --git a/docs/examples/webpack/babel.config.js b/docs/examples/webpack/babel.config.js
@@ -4,9 +4,11 @@
  * @type {import('@babel/core').ConfigFunction}
  */
 module.exports = function (api) {
- const browserslistEnv = !api.env('test')
- ? 'javascripts'
- : 'node'
+ const isBrowser = !api.env('test')
+
+ // Apply Browserslist environment for supported targets
+ // https://github.com/browserslist/browserslist#configuring-for-different-environments
+ const browserslistEnv = isBrowser ? 'javascripts' : 'node'
 
  return {
  presets: [
@@ -17,10 +19,10 @@ module.exports = function (api) {
  bugfixes: true,
 
  // Apply smaller "loose" transforms for browsers
- loose: browserslistEnv === 'javascripts',
+ loose: isBrowser,
 
- // Transform ES modules for Node.js
- modules: browserslistEnv === 'node' ? 'auto' : false
+ // Skip ES module transforms for browsers
+ modules: isBrowser ? false : 'auto'
  }]
  ]
  }

diff --git a/packages/govuk-frontend/babel.config.js b/packages/govuk-frontend/babel.config.js
@@ -4,9 +4,11 @@
  * @type {import('@babel/core').ConfigFunction}
  */
 module.exports = function (api) {
- const browserslistEnv = !api.env('test')
- ? 'javascripts'
- : 'node'
+ const isBrowser = !api.env('test')
+
+ // Apply Browserslist environment for supported targets
+ // https://github.com/browserslist/browserslist#configuring-for-different-environments
+ const browserslistEnv = isBrowser ? 'javascripts' : 'node'
 
  return {
  presets: [
@@ -17,10 +19,10 @@ module.exports = function (api) {
  bugfixes: true,
 
  // Apply smaller "loose" transforms for browsers
- loose: browserslistEnv === 'javascripts',
+ loose: isBrowser,
 
- // Transform ES modules for Node.js
- modules: browserslistEnv === 'node' ? 'auto' : false
+ // Skip ES module transforms for browsers
+ modules: isBrowser ? false : 'auto'
  }]
  ]
  }