使用ES6中class模仿Vue做出双向绑定

最终效果如下：

构造器(constructor)

构造一个TinyVue对象，包含基本的el，data，methods

class TinyVue{
 constructor({el, data, methods}){
  this.$data = data
  this.$el = document.querySelector(el)
  this.$methods = methods
  // 初始化
  this._compile()
  this._updater()
  this._watcher()
 }
}

编译器(compile)

用于解析绑定到输入框和下拉框的v-model和元素的点击事件@click。

先创建一个函数用来载入事件：

// el为元素tagName，attr为元素属性（v-model，@click）
_initEvents(el, attr, callBack) {
 this.$el.querySelectorAll(el).forEach(i => {
  if(i.hasAttribute(attr)) {
   let key = i.getAttribute(attr)
   callBack(i, key)
  }
 })
}

载入输入框事件

this._initEvents('input, textarea', 'v-model', (i, key) => {
 i.addEventListener('input', () => {
  Object.assign(this.$data, {[key]: i.value})
 })
})

载入选择框事件

this._initEvents('select', 'v-model', (i, key) => {
 i.addEventListener('change', () => Object.assign(this.$data, {[key]: i.options[i.options.selectedIndex].value}))
})

载入点击事件

点击事件对应的是methods中的事件

this._initEvents('*', '@click', (i, key) => {
 i.addEventListener('click', () => this.$methods[key].bind(this.$data)())
})

视图更新器(updater)

同理先创建公共函数来处理不同元素中的视图，包括input、textarea的value，select的选择值，p的innerHTML

_initView(el, attr, callBack) {
 this.$el.querySelectorAll(el, attr, callBack).forEach(i => {
  if(i.hasAttribute(attr)) {
   let key = i.getAttribute(attr),
    data = this.$data[key]
   callBack(i, key, data)
  }
 })
}

更新输入框视图

this._initView('input, textarea', 'v-model', (i, key, data) => {
 i.value = data
})

更新选择框视图

this._initView('select', 'v-model', (i, key, data) => {
 i.querySelectorAll('option').forEach(v => {
  if(v.value == data) v.setAttribute('selected', true)
  else v.removeAttribute('selected')
 })
})

更新innerHTML

这里实现方法有点low，仅想到正则替换{{text}}

let regExpInner = /\{{ *([\w_\-]+) *\}}/g
this.$el.querySelectorAll("*").forEach(i => {
 let replaceList = i.innerHTML.match(regExpInner) || (i.hasAttribute('vueID') && i.getAttribute('vueID').match(regExpInner))
 if(replaceList) {
  if(!i.hasAttribute('vueID')) {
   i.setAttribute('vueID', i.innerHTML)
  }
  i.innerHTML = i.getAttribute('vueID')
  replaceList.forEach(v => {
   let key = v.slice(2, v.length - 2)
   i.innerHTML = i.innerHTML.replace(v, this.$data[key])
  })
 }
})

监听器(watcher)

数据变化之后更新视图

<p id="app">
 <input type="text" v-model="text1"><br>
 <input type="text" v-model="text2"><br>
 <textarea type="text" v-model="text3"></textarea><br>
 <button @click="add">加一</button>
 <h1>您输入的是：{{text1}}+{{text2}}+{{text3}}</h1>
 <select v-model="select">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
 </select>
 <select v-model="select">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
 </select>
 <h1>您选择了：{{select}}</h1>
</p>
<script src="./TinyVue.js"></script>
<script>
 let app = new TinyVue({
  el: '#app',
  data: {
   text1: 123,
   text2: 456,
   text3: '文本框',
   select: 'saab'
  },
  methods: {
   add() {
    this.text1 ++
    this.text2 ++
   }
  }
 })
</script>

TinyVue全部代码

class TinyVue{
 constructor({el, data, methods}){
  this.$data = data
  this.$el = document.querySelector(el)
  this.$methods = methods
  this._compile()
  this._updater()
  this._watcher()
 }
 _watcher(data = this.$data) {
  let that = this
  Object.keys(data).forEach(i => {
   let value = data[i]
   Object.defineProperty(data, i, {
    enumerable: true,
    configurable: true,
    get: function () {
     return value;
    },
    set: function (newVal) {
     if (value !== newVal) {
      value = newVal;
      that._updater()
     }
    }
   })
  })
 }
 _initEvents(el, attr, callBack) {
  this.$el.querySelectorAll(el).forEach(i => {
   if(i.hasAttribute(attr)) {
    let key = i.getAttribute(attr)
    callBack(i, key)
   }
  })
 }
 _initView(el, attr, callBack) {
  this.$el.querySelectorAll(el, attr, callBack).forEach(i => {
   if(i.hasAttribute(attr)) {
    let key = i.getAttribute(attr),
     data = this.$data[key]
    callBack(i, key, data)
   }
  })
 }
 _updater() {
  this._initView('input, textarea', 'v-model', (i, key, data) => {
   i.value = data
  })
  this._initView('select', 'v-model', (i, key, data) => {
   i.querySelectorAll('option').forEach(v => {
    if(v.value == data) v.setAttribute('selected', true)
    else v.removeAttribute('selected')
   })
  })
  let regExpInner = /\{{ *([\w_\-]+) *\}}/g
  this.$el.querySelectorAll("*").forEach(i => {
   let replaceList = i.innerHTML.match(regExpInner) || (i.hasAttribute('vueID') && i.getAttribute('vueID').match(regExpInner))
   if(replaceList) {
    if(!i.hasAttribute('vueID')) {
     i.setAttribute('vueID', i.innerHTML)
    }
    i.innerHTML = i.getAttribute('vueID')
    replaceList.forEach(v => {
     let key = v.slice(2, v.length - 2)
     i.innerHTML = i.innerHTML.replace(v, this.$data[key])
    })
   }
  })
 }
 _compile() {
  this._initEvents('*', '@click', (i, key) => {
   i.addEventListener('click', () => this.$methods[key].bind(this.$data)())
  })
  this._initEvents('input, textarea', 'v-model', (i, key) => {
   i.addEventListener('input', () => {
    Object.assign(this.$data, {[key]: i.value})
   })
  })
  this._initEvents('select', 'v-model', (i, key) => {
   i.addEventListener('change', () => Object.assign(this.$data, {[key]: i.options[i.options.selectedIndex].value}))
  })
 }
}

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