fix: better source map handling for webpack

package.json

@@ -31,14 +31,11 @@
     "webpack-virtual-modules": "^0.4.3"
   },
   "devDependencies": {
-    "@babel/core": "^7.15.0",
-    "@babel/preset-env": "^7.15.0",
     "@nuxtjs/eslint-config-typescript": "^6.0.1",
     "@types/express": "^4.17.13",
     "@types/fs-extra": "^9.0.12",
     "@types/jest": "^27.0.1",
     "@types/node": "^16.7.1",
-    "babel-loader": "^8.2.2",
     "chalk": "^4.1.2",
     "enhanced-resolve": "^5.8.2",
     "eslint": "^7.32.0",

src/types.ts

@@ -1,4 +1,4 @@
-import type { Plugin as RollupPlugin, PluginContextMeta as RollupContextMeta } from 'rollup'
+import type { Plugin as RollupPlugin, PluginContextMeta as RollupContextMeta, SourceMap } from 'rollup'
 import type { Compiler as WebpackCompiler, WebpackPluginInstance } from 'webpack'
 import type { Plugin as VitePlugin } from 'vite'
 import type VirtualModulesPlugin from 'webpack-virtual-modules'
@@ -11,12 +11,14 @@ export {
 
 export type Thenable<T> = T | Promise<T>
 
+export type TransformResult = string | { code: string; map?: SourceMap | null; } | null | undefined
+
 export interface UnpluginOptions {
   name: string;
   enforce?: 'post' | 'pre' | undefined;
   transformInclude?: (id: string) => boolean;
-  transform?: (this: UnpluginContext, code: string, id: string) => Thenable<string | { code: string; map: any; } | null | undefined>;
-  load?: (this: UnpluginContext, id: string) => Thenable<string | null | undefined>
+  transform?: (this: UnpluginContext, code: string, id: string) => Thenable<TransformResult>;
+  load?: (this: UnpluginContext, id: string) => Thenable<TransformResult>
   resolveId?: (id: string, importer?: string) => Thenable<string | null | undefined>
 
   // framework specify extends

src/webpack/loaders/load.ts

@@ -1,13 +1,13 @@
 import type { LoaderContext } from 'webpack'
 import { UnpluginContext } from '../../types'
 
-export default async function load (this: LoaderContext<any>, source: string) {
+export default async function load (this: LoaderContext<any>, source: string, map: any) {
   const callback = this.async()
   const { unpluginName } = this.query
   const plugin = this._compiler?.$unpluginContext[unpluginName]
 
   if (!plugin?.load) {
-    return callback(null, source)
+    return callback(null, source, map)
   }
 
   const context: UnpluginContext = {
@@ -23,8 +23,10 @@ export default async function load (this: LoaderContext<any>, source: string) {
   const res = await plugin.load.call(context, id)
 
   if (res == null) {
-    callback(null, source)
+    callback(null, source, map)
+  } else if (typeof res !== 'string') {
+    callback(null, res.code, res.map ?? map)
   } else {
-    callback(null, res)
+    callback(null, res, map)
   }
 }

src/webpack/loaders/transform.ts

@@ -19,7 +19,7 @@ export default async function transform (this: LoaderContext<any>, source: strin
   if (res == null) {
     callback(null, source, map)
   } else if (typeof res !== 'string') {
-    callback(null, res.code, res.map)
+    callback(null, res.code, res.map ?? map)
   } else {
     callback(null, res, map)
   }