feat: add plugin-legacy, as the main use case for v2 is for IE11 support

Author: haoqunjiang

template/base/package.json

@@ -9,10 +9,11 @@
     "vue": "^2.6.14"
   },
   "devDependencies": {
+    "@vitejs/plugin-legacy": "^1.6.3",
     "@vue/runtime-dom": "^3.2.22",
     "unplugin-vue2-script-setup": "^0.7.1",
-    "vite-plugin-vue2": "^1.9.0",
     "vite": "^2.6.14",
+    "vite-plugin-vue2": "^1.9.0",
     "vue-template-compiler": "^2.6.14"
   }
 }

template/base/vite.config.js

@@ -1,6 +1,7 @@
 import { fileURLToPath } from 'url'
 
 import { defineConfig } from 'vite'
+import legacy from '@vitejs/plugin-legacy'
 import { createVuePlugin as vue2 } from 'vite-plugin-vue2'
 import scriptSetup from 'unplugin-vue2-script-setup/vite'
 
@@ -10,7 +11,11 @@ export default defineConfig({
     vue2({
       jsx: true
     }),
-    scriptSetup()
+    scriptSetup(),
+    legacy({
+      targets: ['ie >= 11'],
+      additionalLegacyPolyfills: ['regenerator-runtime/runtime']
+    })
   ],
   resolve: {
     alias: {