feat: warn user if config includes cjs format (#403)

Gugustinette · sxzz · web-flow · commit bd42eda1db07 · 2025-08-04T23:46:57.000+08:00
Co-authored-by: Kevin Deng &lt;sxzz@sxzz.moe&gt;
diff --git a/src/features/cjs.ts b/src/features/cjs.ts
@@ -0,0 +1,28 @@
+import coerce from 'semver/functions/coerce.js'
+import satisfies from 'semver/functions/satisfies.js'
+import type { ResolvedOptions } from '../options'
+
+/**
+ * If the config includes the `cjs` format and
+ * one of its target >= node 23.0.0 / 22.12.0,
+ * warn the user about the deprecation of CommonJS.
+ */
+export function warnLegacyCJS(config: ResolvedOptions): void {
+  if (!config.format.includes('cjs') || !config.target) {
+    return
+  }
+
+  const legacy = config.target.some((t) => {
+    const version = coerce(t.split('node')[1])
+    return version && satisfies(version, '>=23.0.0 || >=22.12.0')
+  })
+
+  if (legacy) {
+    config.logger.warnOnce(
+      'We recommend using the ESM format instead of CommonJS.\n' +
+        'The ESM format is compatible with modern platforms and runtimes, ' +
+        'and most new libraries are now distributed only in ESM format.\n' +
+        'Learn more at https://nodejs.org/en/learn/modules/publishing-a-package#how-did-we-get-here',
+    )
+  }
+}
diff --git a/src/index.ts b/src/index.ts
@@ -11,6 +11,7 @@ import {
 import { exec } from 'tinyexec'
 import treeKill from 'tree-kill'
 import { attw } from './features/attw'
+import { warnLegacyCJS } from './features/cjs'
 import { cleanOutDir } from './features/clean'
 import { copy } from './features/copy'
 import { writeExports, type TsdownChunks } from './features/exports'
@@ -103,6 +104,8 @@ export async function buildSingle(
 
   const { hooks, context } = await createHooks(config)
 
+  warnLegacyCJS(config)
+
   await rebuild(true)
   if (watch) {
     return () => rebuild()
diff --git a/src/utils/logger.ts b/src/utils/logger.ts
@@ -30,6 +30,8 @@ function format(msgs: any[]) {
   return msgs.filter((arg) => arg !== undefined && arg !== false).join(' ')
 }
 
+const warnedMessages = new Set<string>()
+
 export function createLogger(
   level: LogLevel = 'info',
   { customLogger, console = globalThis.console }: LoggerOptions = {},
@@ -46,8 +48,6 @@ export function createLogger(
     console[method](msg)
   }
 
-  const warnedMessages = new Set<string>()
-
   const logger: Logger = {
     level,
 

Original file line number	Diff line number	Diff line change
`@@ -30,6 +30,8 @@ function format(msgs: any[]) {`
`30`	`30`	`return msgs.filter((arg) => arg !== undefined && arg !== false).join(' ')`
`31`	`31`	`}`
`32`	`32`
	`33`	`+const warnedMessages = new Set<string>()`
	`34`	`+`
`33`	`35`	`export function createLogger(`
`34`	`36`	`level: LogLevel = 'info',`
`35`	`37`	`{ customLogger, console = globalThis.console }: LoggerOptions = {},`
`@@ -46,8 +48,6 @@ export function createLogger(`
`46`	`48`	`console[method](msg)`
`47`	`49`	`}`
`48`	`50`
`49`		`- const warnedMessages = new Set<string>()`
`50`		`-`
`51`	`51`	`const logger: Logger = {`
`52`	`52`	`level,`
`53`	`53`