cache context.style access

Author: yyx990803

lib/addStylesServer.js

@@ -8,10 +8,12 @@ module.exports = function (parentId, list, isProduction) {
     if (!styles) {
       styles = context._styles = {}
       Object.defineProperty(context, 'styles', {
+        enumberable: true,
         get () {
-          return Object.keys(styles)
-            .map(id => renderStyleTag(styles[id]))
-            .join('\n')
+          return (
+            context._renderedStyles ||
+            (context._renderedStyles = renderStyles(styles))
+          )
         }
       })
     }
@@ -65,6 +67,15 @@ function addStyleDev (styles, list) {
   }
 }
 
-function renderStyleTag (style) {
-  return `<style data-vue-ssr-id="${style.ids.join(' ')}"${style.media ? ` media=${style.mdia}` : ''}>${style.css}</style>`
+function renderStyles (styles) {
+  var css = ''
+  for (var key in styles) {
+    var style = styles[key]
+    css += `<style data-vue-ssr-id="${
+      style.ids.join(' ')
+    }"${
+      style.media ? ` media=${style.mdia}` : ''
+    }>${style.css}</style>`
+  }
+  return css
 }