feat: handle .mjs as type="module"

Author: pi0

src/renderer.ts

@@ -1,5 +1,5 @@
 import { createMapper, AsyncFileMapper } from './mapper'
-import { normalizeFile, isCSS, isJS, ensureTrailingSlash } from './utils'
+import { normalizeFile, isCSS, isJS, isModule, ensureTrailingSlash } from './utils'
 
 export type ClientManifest = {
   publicPath: string;
@@ -144,7 +144,7 @@ export function renderScripts (ssrContext: SSRContext, renderContext: RenderCont
     const async = (getUsedAsyncFiles(ssrContext, renderContext) || []).filter(({ file }) => isJS(file))
     const needed = [initial[0]].concat(async, initial.slice(1))
     return needed.map(({ file }) => {
-      return `<script src="${renderContext.publicPath}${file}" defer></script>`
+      return `<script${isModule(file) ? ' type="module" ' : ''}src="${renderContext.publicPath}${file}" defer></script>`
     }).join('')
   } else {
     return ''

src/utils.ts

@@ -1,13 +1,18 @@
 import { Resource } from './renderer'
 
 const IS_JS_RE = /\.[cm]?js(\?[^.]+)?$/
+const IS_MODULE_RE = /\.mjs(\?[^.]+)?$/
 const HAS_EXT_RE = /[^./]+\.[^./]+$/
 const IS_CSS_RE = /\.css(\?[^.]+)?$/
 
 export function isJS (file: string) {
   return IS_JS_RE.test(file) || !HAS_EXT_RE.test(file)
 }
 
+export function isModule (file: string) {
+  return IS_MODULE_RE.test(file) || !HAS_EXT_RE.test(file)
+}
+
 export function isCSS (file: string) {
   return IS_CSS_RE.test(file)
 }