feat: allow output.fileName to be a function

Author: egoist

src/index.ts

@@ -32,7 +32,8 @@ import {
   Format,
   ConfigEntryObject,
   Env,
-  ConfigOutput
+  ConfigOutput,
+  FileNameContext
 } from './types'
 
 // Make rollup-plugin-vue use basename in component.__file instead of absolute path
@@ -197,7 +198,9 @@ export class Bundler {
 
     // UMD format should always bundle node_modules
     const bundleNodeModules =
-      format === 'umd' || format === 'iife' || config.bundleNodeModules
+      rollupFormat === 'umd' ||
+      rollupFormat === 'iife' ||
+      config.bundleNodeModules
 
     plugins.push(
       nodeResolvePlugin({
@@ -384,15 +387,14 @@ export class Bundler {
       }
     })
 
-    const isESM = /^esm?$/.test(format)
-
-    const fileName =
-      config.output.fileName ||
-      (format === 'cjs' || isESM
-        ? `[name][min][ext]`
-        : `[name].[format][min][ext]`)
-
-    const extPlaceholder = isESM ? '.mjs' : '.js'
+    const getFileName = config.output.fileName || defaultGetFileName
+    const fileNameTemplate =
+      typeof getFileName === 'function'
+        ? getFileName({ format: rollupFormat, minify })
+        : getFileName
+    const fileName = fileNameTemplate
+      .replace(/\[min\]/, minPlaceholder)
+      .replace(/\[ext\]/, /^esm?$/.test(rollupFormat) ? '.mjs' : '.js')
 
     return {
       inputConfig: {
@@ -424,9 +426,7 @@ export class Bundler {
         globals: config.globals,
         format: rollupFormat,
         dir: path.resolve(config.output.dir || 'dist'),
-        entryFileNames: fileName
-          .replace(/\[min\]/, minPlaceholder)
-          .replace(/\[ext\]/, extPlaceholder),
+        entryFileNames: fileName,
         name: config.output.moduleName,
         banner,
         sourcemap:
@@ -654,4 +654,11 @@ async function printAssets(assets: Assets, title: string) {
   )
 }
 
+function defaultGetFileName({ format }: FileNameContext) {
+  const isESM = /^esm?$/.test(format)
+  return format === 'cjs' || isESM
+    ? `[name][min][ext]`
+    : `[name].[format][min][ext]`
+}
+
 export { Config, NormalizedConfig, Options, ConfigOutput }

src/types.ts

@@ -35,6 +35,13 @@ export type ExtendConfig = (
   { format, input }: { format: Format; input: string[] | ConfigEntryObject }
 ) => NormalizedConfig
 
+export interface FileNameContext {
+  format: RollupFormat
+  minify: boolean
+}
+
+export type GetFileName = (context: FileNameContext) => string
+
 export interface BabelPresetOptions {
   /**
    * Transform `async/await` to `Promise`.
@@ -92,9 +99,13 @@ export interface ConfigOutput {
    * - `[format]`: The output format. (without `-min` suffix)
    * - `[ext]`: The extension. It's `.mjs` for `esm` format, `.js` otherwise
    * - `[min]`: It will replaced by `.min` when the format ends with `-min`, otherwise it's an empty string.
+   *
+   * The value can also be a function which returns the fileName template,
+   * The placeholders are also available in the return value.
+   *
    * @cli `--file-name <fileName>`
    */
-  fileName?: string
+  fileName?: string | GetFileName
   /**
    * Module name for umd bundle
    */

test/__snapshots__/index.test.ts.snap

@@ -256,7 +256,7 @@ module.exports = index;
 "
 `;
 
-exports[`uglify: uglify dist/index.cjs.min.js 1`] = `
+exports[`uglify: uglify dist/index.min.js 1`] = `
 "\\"use strict\\";Object.defineProperty(exports,\\"__esModule\\",{value:!0});const a=1;exports.a=1;
 "
 `;