feat(data-loader): defineLoader() type helper

__tests__/e2e/static-data/static.data.ts

@@ -1,9 +1,10 @@
 import fs from 'fs'
+import { defineLoader } from 'vitepress'
 
 type Data = Record<string, boolean>[]
 export declare const data: Data
 
-export default {
+export default defineLoader({
   watch: ['./data/*'],
   async load(files: string[]): Promise<Data> {
     const foo = fs.readFileSync(
@@ -16,4 +17,4 @@ export default {
     )
     return [JSON.parse(foo), JSON.parse(bar)]
   }
-}
+})

src/node/index.ts

@@ -4,6 +4,7 @@ export * from './markdown'
 export * from './build/build'
 export * from './serve/serve'
 export * from './init/init'
+export { defineLoader, type LoaderModule } from './plugins/staticDataPlugin'
 
 // shared types
 export type {

src/node/plugins/staticDataPlugin.ts

@@ -12,11 +12,18 @@ const loaderMatch = /\.data\.(j|t)s$/
 
 let server: ViteDevServer
 
-interface LoaderModule {
+export interface LoaderModule {
   watch?: string[] | string
   load: (watchedFiles: string[]) => any
 }
 
+/**
+ * Helper for defining loaders with type inference
+ */
+export function defineLoader(loader: LoaderModule) {
+  return loader
+}
+
 const idToLoaderModulesMap: Record<string, LoaderModule | undefined> =
   Object.create(null)