handle older versions of Vue

Author: yyx990803

lib/hot-shim.js renamed to lib/hot-reload-api.js

@@ -9,10 +9,22 @@ var shimmed = false
 exports.install = function (Vue) {
   if (shimmed) return
   shimmed = true
-  console.log('[HMR] Vue component hot reload shim applied.')
+
+  exports.compatible = !!Vue.internalDirectives
+  if (!exports.compatible) {
+    console.warn(
+      '[HMR] vue-loader hot reload is only compatible with ' +
+      'Vue.js 1.0.0+.'
+    )
+    return
+  }
+
+  // create global hot reload map
   var map = Vue.config._hotComponents = Object.create(null)
+  // check compatibility
   var componentDir = Vue.internalDirectives.component
-
+  
+  // shim the component directive
   var set = componentDir.setComponent
   componentDir.setComponent = function (id, cb) {
     var prevComponent = this.Component
@@ -50,6 +62,8 @@ exports.install = function (Vue) {
     }
     unbind.call(this)
   }
+
+  console.log('[HMR] Vue component hot reload shim applied.')
 }
 
 /**

lib/loader.js

@@ -137,8 +137,9 @@ module.exports = function (content) {
             // shim the component directive so that it
             // registers the instances
             'var Vue = require("vue")\n' +
-            'var shim = require("' + require.resolve('./hot-shim') + '")\n' +
-            'shim.install(Vue)\n' +
+            'var hotAPI = require("' + require.resolve('./hot-reload-api') + '")\n' +
+            'hotAPI.install(Vue)\n' +
+            'if (!hotAPI.compatible) return\n' +
             'var map = Vue.config._hotComponents\n' +
             'var id = module.exports.hotID = ' + (scriptString || templateString) + '\n' +
             'module.hot.accept(' + JSON.stringify(accepted) + ', function () {\n' +
@@ -149,7 +150,7 @@ module.exports = function (content) {
               // reset linker
               'Ctor.linker = null\n' +
               // reload directive instances
-              'map[id].instances.forEach(shim.update)\n' +
+              'map[id].instances.forEach(hotAPI.update)\n' +
               // re-enable transitions
             '})\n' +
           '})()\n' +