fix canonical url

packages/nuxt/pages/post/_.vue

@@ -59,6 +59,65 @@ import '~/assets/remark42'
       post: r,
     }
   },
+  head() {
+    const { title: _title, content, tag, image } = this.post
+    const title = `${_title} - ${THEME.title}`
+    const description = content.substr(0, 140)
+
+    return {
+      title,
+      meta: [
+        {
+          hid: 'description',
+          name: 'description',
+          content: description,
+        },
+        ...(tag
+          ? [
+              {
+                hid: 'keywords',
+                name: 'keywords',
+                content: tag.join(','),
+              },
+            ]
+          : []),
+        {
+          hid: 'og:title',
+          property: 'og:title',
+          content: title,
+        },
+        {
+          hid: 'og:description',
+          property: 'og:description',
+          content: description,
+        },
+        {
+          hid: 'twitter:title',
+          property: 'twitter:title',
+          content: title,
+        },
+        {
+          hid: 'twitter:description',
+          property: 'twitter:description',
+          content: description,
+        },
+        ...(image
+          ? [
+              {
+                hid: 'og:image',
+                property: 'og:image',
+                content: image,
+              },
+              {
+                hid: 'twitter:image',
+                property: 'twitter:image',
+                content: image,
+              },
+            ]
+          : []),
+      ],
+    }
+  },
   mounted() {
     this.initRemark42()
   },
@@ -69,14 +128,14 @@ import '~/assets/remark42'
   },
 })
 export default class PostPage extends Vue {
-  post: {
+  post!: {
     date?: string
     title: string
     image?: string
     tag?: string[]
     category?: string[]
     content: string
-  } | null = null
+  }
 
   theme = THEME