From 0d08f0dba92dfa524e779fe392150167913b6a55 Mon Sep 17 00:00:00 2001
From: Declan de Wet <declandewet@me.com>
Date: Tue, 1 Nov 2016 19:18:58 +0200
Subject: [PATCH] refactor code to be more modular & performant

---
 .editorconfig                  |   4 +-
 README.md                      |   2 +-
 package.json                   |   6 +-
 src/$meta.js                   |  11 ++
 src/generateServerInjector.js  |  34 +++++
 src/getComponentOption.js      |  50 ++++++++
 src/getMetaInfo.js             |  35 ++++++
 src/index.js                   | 224 +++------------------------------
 src/inject.js                  |  20 +++
 src/updateClientMetaInfo.js    |  16 +++
 src/updateHtmlTagAttributes.js |  35 ++++++
 src/updateTitleTag.js          |   8 ++
 12 files changed, 236 insertions(+), 209 deletions(-)
 create mode 100644 src/$meta.js
 create mode 100644 src/generateServerInjector.js
 create mode 100644 src/getComponentOption.js
 create mode 100644 src/getMetaInfo.js
 create mode 100644 src/inject.js
 create mode 100644 src/updateClientMetaInfo.js
 create mode 100644 src/updateHtmlTagAttributes.js
 create mode 100644 src/updateTitleTag.js

diff --git a/.editorconfig b/.editorconfig
index fec6292..4a7ea30 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -5,8 +5,8 @@ indent_style = space
 indent_size = 2
 end_of_line = lf
 charset = utf-8
-trim_trailing_whitespace = false
+trim_trailing_whitespace = true
 insert_final_newline = true
 
 [*.md]
-trim_trailing_whitespace = false
\ No newline at end of file
+trim_trailing_whitespace = false
diff --git a/README.md b/README.md
index 0b8aaf1..7bb0f5a 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 <p align="center">
-  <img src="http://imgh.us/Group_5.svg" alt="vue-meta">
+  <img src="http://imgur.com/258WtHI.png" alt="vue-meta">
 </p>
 
 <h5 align="center">
diff --git a/package.json b/package.json
index 9aef143..e21363f 100644
--- a/package.json
+++ b/package.json
@@ -85,7 +85,11 @@
       "define",
       "describe",
       "it",
-      "expect"
+      "expect",
+      "before",
+      "beforeEach",
+      "after",
+      "afterEach"
     ]
   }
 }
diff --git a/src/$meta.js b/src/$meta.js
new file mode 100644
index 0000000..908a537
--- /dev/null
+++ b/src/$meta.js
@@ -0,0 +1,11 @@
+import inject from './inject'
+
+/**
+ * Returns an injector for server-side rendering.
+ * @this {Object} - the Vue instance (a root component)
+ * @return {Object} - injector
+ */
+export default function $meta () {
+  // bind inject method to this component
+  return { inject: inject.bind(this) }
+}
diff --git a/src/generateServerInjector.js b/src/generateServerInjector.js
new file mode 100644
index 0000000..d303812
--- /dev/null
+++ b/src/generateServerInjector.js
@@ -0,0 +1,34 @@
+import { VUE_META_ATTRIBUTE } from './constants'
+
+/**
+ * Converts a meta info property to one that can be stringified on the server
+ *
+ * @param  {String} type - the type of data to convert
+ * @param  {(String|Object|Array<Object>)} data - the data value
+ * @return {Object} - the new injector
+ */
+export default function generateServerInjector (type, data) {
+  console.log('server injector called for', type, 'with', data)
+  switch (type) {
+    case 'title':
+      return {
+        toString: () => `<${type} ${VUE_META_ATTRIBUTE}="true">${data}</${type}>`
+      }
+    case 'htmlAttrs': {
+      return {
+        toString () {
+          let attributeStr = ''
+          let watchedAttrs = []
+          for (let attr in data) {
+            if (data.hasOwnProperty(attr)) {
+              watchedAttrs.push(attr)
+              attributeStr += `${typeof data[attr] !== 'undefined' ? `${attr}="${data[attr]}"` : attr} `
+            }
+          }
+          attributeStr += `${VUE_META_ATTRIBUTE}="${watchedAttrs.join(',')}"`
+          return attributeStr.trim()
+        }
+      }
+    }
+  }
+}
diff --git a/src/getComponentOption.js b/src/getComponentOption.js
new file mode 100644
index 0000000..7c7274e
--- /dev/null
+++ b/src/getComponentOption.js
@@ -0,0 +1,50 @@
+import deepmerge from 'deepmerge'
+
+/**
+ * Returns the `opts.option` $option value of the given `opts.component`.
+ * If methods are encountered, they will be bound to the component context.
+ * If `opts.deep` is true, will recursively merge all child component
+ * `opts.option` $option values into the returned result.
+ *
+ * @param  {Object} opts - options
+ * @param  {Object} opts.component - Vue component to fetch option data from
+ * @param  {String} opts.option - what option to look for
+ * @param  {Boolean} opts.deep - look for data in child components as well?
+ * @param  {Object} [result={}] - result so far
+ * @return {Object} - final aggregated result
+ */
+export default function getComponentOption (opts, result = {}) {
+  const { component, option, deep } = opts
+  const { $options } = component
+
+  // only collect option data if it exists
+  if ($options[option]) {
+    const data = $options[option]
+
+    // TODO: check data is plain object, throw if not
+
+    // bind context of option methods (if any) to this component
+    for (const key in data) {
+      if (data.hasOwnProperty(key)) {
+        const value = data[key]
+        if (typeof value === 'function') {
+          data[key] = value.bind(component)
+        }
+      }
+    }
+
+    // merge with existing options
+    result = deepmerge(result, data)
+  }
+
+  // collect & aggregate child options if deep = true
+  if (deep) {
+    const { $children } = component
+    for (let i = 0, len = $children.length; i < len; i++) {
+      const component = $children[i]
+      result = getComponentOption({ option, deep, component }, result)
+    }
+  }
+
+  return result
+}
diff --git a/src/getMetaInfo.js b/src/getMetaInfo.js
new file mode 100644
index 0000000..46a6836
--- /dev/null
+++ b/src/getMetaInfo.js
@@ -0,0 +1,35 @@
+import getComponentOption from './getComponentOption'
+
+/**
+ * Returns the correct meta info for the given component
+ * (child components will overwrite parent meta info)
+ *
+ * @param  {Object} component - the Vue instance to get meta info from
+ * @return {Object} - returned meta info
+ */
+export default function getMetaInfo (component) {
+  // collect & aggregate all metaInfo $options
+  const info = getComponentOption({ component, option: 'metaInfo', deep: true })
+
+  // if any info options are a function, coerce them to the result of a call
+  for (let key in info) {
+    if (info.hasOwnProperty(key)) {
+      const value = info[key]
+      if (typeof value === 'function') {
+        info[key] = value()
+      }
+    }
+  }
+
+  // backup the title chunk
+  if (info.title) {
+    info.titleChunk = info.title
+  }
+
+  // replace title with populated template
+  if (info.titleTemplate && info.titleChunk) {
+    info.title = info.titleTemplate.replace(/%s/g, info.titleChunk)
+  }
+
+  return info
+}
diff --git a/src/index.js b/src/index.js
index c399534..6cb0f56 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,210 +1,24 @@
-import deepMerge from 'deepmerge'
-import { VUE_META_ATTRIBUTE } from './constants'
+import $meta from './$meta'
+import getMetaInfo from './getMetaInfo'
+import updateClientMetaInfo from './updateClientMetaInfo'
 
-// initialize vue-meta
-const VueMeta = {}
-
-// initialize manager
-const _manager = {}
-
-/**
- * Registers the plugin with Vue.js
- * Pass it like so: Vue.use(VueMeta)
- * @param {Function} Vue - the Vue constructor
- */
-VueMeta.install = function install (Vue) {
-  // if we've already installed, don't do anything
-  if (VueMeta.install.installed) return
-
-  // set installation inspection flag
-  VueMeta.install.installed = true
-
-  // listen for when components mount - when they do,
-  // update the meta info & the DOM
-  Vue.mixin({
-    mounted () {
-      this.$root.$meta().updateMetaInfo()
-    }
-  })
-
-  /**
-   * returns a cached manager API for use on the server
-   * @return {Object} - manager (The programmatic API for this module)
-   */
-  Vue.prototype.$meta = function $meta () {
-    _manager.getMetaInfo = _manager.getMetaInfo || Vue.util.bind(getMetaInfo, this)
-    _manager.updateMetaInfo = _manager.updateMetaInfo || updateMetaInfo
-    _manager.inject = _manager.inject || inject
-    return _manager
-  }
-
-  /**
-   * Converts the state of the meta info object such that each item
-   * can be compiled to a tag string on the server
-   * @return {Object} - server meta info with `toString` methods
-   */
-  function inject () {
-    const info = this.getMetaInfo()
-    const serverMetaInfo = {}
-    for (let key in info) {
-      if (info.hasOwnProperty(key)) {
-        serverMetaInfo[key] = generateServerInjector(key, info[key])
-      }
-    }
-    return serverMetaInfo
-  }
-
-  /**
-   * Converts a meta info property to one that can be stringified on the server
-   * @param  {String} type - the type of data to convert
-   * @param  {(String|Object|Array<Object>)} data - the data value
-   * @return {Object} - the new injector
-   */
-  function generateServerInjector (type, data) {
-    switch (type) {
-      case 'title':
-        return {
-          toString: () => `<${type} ${VUE_META_ATTRIBUTE}="true">${data}</${type}>`
-        }
-      case 'htmlAttrs': {
-        return {
-          toString () {
-            let attributeStr = ''
-            let watchedAttrs = []
-            for (let attr in data) {
-              if (data.hasOwnProperty(attr)) {
-                watchedAttrs.push(attr)
-                attributeStr += `${typeof data[attr] !== 'undefined' ? `${attr}="${data[attr]}"` : attr} `
-              }
-            }
-            attributeStr += `${VUE_META_ATTRIBUTE}="${watchedAttrs.join(',')}"`
-            return attributeStr.trim()
-          }
-        }
-      }
-    }
-  }
-
-  /**
-   * Updates meta info and renders it to the DOM
-   */
-  function updateMetaInfo () {
-    const newMeta = this.getMetaInfo()
-    if (newMeta.title) {
-      updateTitle(newMeta.title)
-    }
-    if (newMeta.htmlAttrs) {
-      updateHtmlAttrs(newMeta.htmlAttrs)
-    }
-  }
-
-  /**
-   * Fetches corresponding meta info for the current component state
-   * @return {Object} - all the meta info for currently matched components
-   */
-  function getMetaInfo () {
-    const info = getMetaInfoDefinition(Vue, this)
-    if (info.titleTemplate) {
-      info.title = info.titleTemplate.replace('%s', info.title)
-    }
-    return info
-  }
-}
-
-/**
- * Recursively traverses each component, checking for a `metaInfo`
- * option. It then merges all these options into one object, giving
- * higher priority to deeply nested components.
- *
- * NOTE: This function uses Vue.prototype.$children, the results of which
- *       are not gauranted to be in order. For this reason, try to avoid
- *       using the same `metaInfo` property in sibling components.
- *
- * @param  {Function} Vue - the Vue constructor
- * @param  {Object} $instance - the current instance
- * @param  {Object} [metaInfo={}] - the merged options
- * @return {Object} metaInfo - the merged options
- */
-function getMetaInfoDefinition (Vue, $instance, metaInfo = {
-  title: '',
-  htmlAttrs: {}
-}) {
-  // if current instance has a metaInfo option...
-  if ($instance.$options.metaInfo) {
-    const componentMetaInfo = $instance.$options.metaInfo
-
-    // ...convert all function type keys to raw data
-    // (this allows meta info to be inferred from props & data)...
-    for (let key in componentMetaInfo) {
-      if (componentMetaInfo.hasOwnProperty(key)) {
-        const val = componentMetaInfo[key]
-        if (typeof val === 'function') {
-          componentMetaInfo[key] = val.call($instance)
-        }
-      }
-    }
-
-    // ...then merge the data into metaInfo
-    metaInfo = deepMerge(metaInfo, componentMetaInfo)
-  }
-
-  // check if any children also have a metaInfo option, if so, merge
-  // them into existing data
-  const len = $instance.$children.length
-  if (len) {
-    for (let i = 0; i < len; i++) {
-      metaInfo = getMetaInfoDefinition(Vue, $instance.$children[i], metaInfo)
-    }
-  }
-
-  // meta info is ready for consumption
-  return metaInfo
-}
-
-/**
- * updates the document title
- * @param  {String} title - the new title of the document
- */
-function updateTitle (title) {
-  document.title = title || document.title
-}
-
-/**
- * updates the document's html tag attributes
- * @param  {Object} attrs - the new document html attributes
- */
-function updateHtmlAttrs (attrs) {
-  const tag = document.getElementsByTagName('html')[0]
-  const vueMetaAttrString = tag.getAttribute(VUE_META_ATTRIBUTE)
-  const vueMetaAttrs = vueMetaAttrString ? vueMetaAttrString.split(',') : []
-  const toRemove = [].concat(vueMetaAttrs)
-  for (let attr in attrs) {
-    if (attrs.hasOwnProperty(attr)) {
-      const val = attrs[attr] || ''
-      tag.setAttribute(attr, val)
-      if (vueMetaAttrs.indexOf(attr) === -1) {
-        vueMetaAttrs.push(attr)
-      }
-      const saveIndex = toRemove.indexOf(attr)
-      if (saveIndex !== -1) {
-        toRemove.splice(saveIndex, 1)
-      }
-    }
-  }
-  let i = toRemove.length - 1
-  for (; i >= 0; i--) {
-    tag.removeAttribute(toRemove[i])
-  }
-  if (vueMetaAttrs.length === toRemove.length) {
-    tag.removeAttribute(VUE_META_ATTRIBUTE)
-  } else {
-    tag.setAttribute(VUE_META_ATTRIBUTE, vueMetaAttrs.join(','))
-  }
-}
-
-// automatic installation when global context
+// automatic install
 if (typeof Vue !== 'undefined') {
   Vue.use(VueMeta)
 }
 
-export default VueMeta
+/**
+ * Plugin install function.
+ * @param {Function} Vue - the Vue constructor.
+ */
+export default function VueMeta (Vue) {
+  // bind the $meta method to this component instance
+  Vue.prototype.$meta = $meta
+
+  // watch for client side updates
+  Vue.mixin({
+    mounted () {
+      updateClientMetaInfo(getMetaInfo(this.$root))
+    }
+  })
+}
diff --git a/src/inject.js b/src/inject.js
new file mode 100644
index 0000000..a95e465
--- /dev/null
+++ b/src/inject.js
@@ -0,0 +1,20 @@
+import getMetaInfo from './getMetaInfo'
+import generateServerInjector from './generateServerInjector'
+
+/**
+ * Converts the state of the meta info object such that each item
+ * can be compiled to a tag string on the server
+ *
+ * @this {Object} - Vue instance - ideally the root component
+ * @return {Object} - server meta info with `toString` methods
+ */
+export default function inject () {
+  const info = getMetaInfo(this.$root)
+  const serverMetaInfo = {}
+  for (let key in info) {
+    if (info.hasOwnProperty(key) && key !== 'titleTemplate') {
+      serverMetaInfo[key] = generateServerInjector(key, info[key])
+    }
+  }
+  return serverMetaInfo
+}
diff --git a/src/updateClientMetaInfo.js b/src/updateClientMetaInfo.js
new file mode 100644
index 0000000..618a966
--- /dev/null
+++ b/src/updateClientMetaInfo.js
@@ -0,0 +1,16 @@
+import updateTitleTag from './updateTitleTag'
+import updateHtmlTagAttributes from './updateHtmlTagAttributes'
+
+/**
+ * Performs client-side updates when new meta info is received
+ *
+ * @param  {Object} newInfo - the meta info to update to
+ */
+export default function updateClientMetaInfo (newInfo) {
+  if (newInfo.title) {
+    updateTitleTag(newInfo.title)
+  }
+  if (newInfo.htmlAttrs) {
+    updateHtmlTagAttributes(newInfo.htmlAttrs)
+  }
+}
diff --git a/src/updateHtmlTagAttributes.js b/src/updateHtmlTagAttributes.js
new file mode 100644
index 0000000..bce573a
--- /dev/null
+++ b/src/updateHtmlTagAttributes.js
@@ -0,0 +1,35 @@
+import { VUE_META_ATTRIBUTE } from './constants'
+
+/**
+ * updates the document's html tag attributes
+ *
+ * @param  {Object} attrs - the new document html attributes
+ */
+export default function updateHtmlTagAttributes (attrs) {
+  const tag = document.getElementsByTagName('html')[0]
+  const vueMetaAttrString = tag.getAttribute(VUE_META_ATTRIBUTE)
+  const vueMetaAttrs = vueMetaAttrString ? vueMetaAttrString.split(',') : []
+  const toRemove = [].concat(vueMetaAttrs)
+  for (let attr in attrs) {
+    if (attrs.hasOwnProperty(attr)) {
+      const val = attrs[attr] || ''
+      tag.setAttribute(attr, val)
+      if (vueMetaAttrs.indexOf(attr) === -1) {
+        vueMetaAttrs.push(attr)
+      }
+      const saveIndex = toRemove.indexOf(attr)
+      if (saveIndex !== -1) {
+        toRemove.splice(saveIndex, 1)
+      }
+    }
+  }
+  let i = toRemove.length - 1
+  for (; i >= 0; i--) {
+    tag.removeAttribute(toRemove[i])
+  }
+  if (vueMetaAttrs.length === toRemove.length) {
+    tag.removeAttribute(VUE_META_ATTRIBUTE)
+  } else {
+    tag.setAttribute(VUE_META_ATTRIBUTE, vueMetaAttrs.join(','))
+  }
+}
diff --git a/src/updateTitleTag.js b/src/updateTitleTag.js
new file mode 100644
index 0000000..f4fc9ed
--- /dev/null
+++ b/src/updateTitleTag.js
@@ -0,0 +1,8 @@
+/**
+ * updates the document title
+ *
+ * @param  {String} title - the new title of the document
+ */
+export default function updateTitleTag (title = document.title) {
+  document.title = title
+}