hot reload: better handle root and non-rendered components

Author: yyx990803

lib/loader.js

@@ -122,6 +122,7 @@ module.exports = function (content) {
       process.env.NODE_ENV !== 'production' &&
       (parts.script.length || parts.template.length)
     ) {
+      var hotReloadAPIPath = require.resolve('./hot-reload-api').replace(/\\/g, "\\\\")
       var scriptString = parts.script.length ? getRequireString('script', parts.script[0], 0) : ''
       var templateString = parts.template.length ? getRequireString('template', parts.template[0], 0, hasLocalStyles) : ''
       var accepted = []
@@ -137,16 +138,25 @@ module.exports = function (content) {
             // shim the component directive so that it
             // registers the instances
             'var Vue = require("vue")\n' +
-            'var hotAPI = require("' + require.resolve('./hot-reload-api') + '")\n' +
+            'var hotAPI = require("' + hotReloadAPIPath + '")\n' +
             'hotAPI.install(Vue)\n' +
             'if (!hotAPI.compatible) return\n' +
             'var map = Vue.config._hotComponents\n' +
             'var id = module.exports.hotID = ' + (scriptString || templateString) + '\n' +
+            // store the record
+            'if (typeof module.exports.el !== "string" && typeof module.exports.data !== "object") {\n' +
+              'map[id] = { Ctor: Vue.extend(module.exports), instances: [] }\n' +
+            '}\n' +
             'module.hot.accept(' + JSON.stringify(accepted) + ', function () {\n' +
+              'if (!map[id]) {\n' +
+                'throw new Error("Root or manually-mounted instance modified. Full reload is required.")\n' +
+              '}\n' +
               'var Ctor = map[id].Ctor\n' +
               // overwrite existing constructor's options
               (scriptString ? 'Ctor.options = Vue.util.mergeOptions(Vue.options, require(' + scriptString + '))\n' : '') +
               (templateString ? 'Ctor.options.template = require(' + templateString + ')\n' : '') +
+              // handle recursive names
+              'if (Ctor.options.name) Ctor.options.components[Ctor.options.name] = Ctor\n' +
               // reset linker
               'Ctor.linker = null\n' +
               // reload directive instances