JavaScript之实现一个简单的Vue示例

var obj = {name:'wclimb'}
var age = 24
Object.defineProperty(obj,'age',{
  enumerable: true, // 可枚举
  configurable: false, // 不能再define
  get () {
    return age
  },
  set (newVal) {
    console.log('我改变了',age +' -> '+newVal);
    age = newVal
  }
})

> obj.age
> 24

> obj.age = 25;
> 我改变了 24 -> 25
> 25

<div id="wrap">
  <p v-html="test"></p>
  <input type="text" v-model="form">
  <input type="text" v-model="form">
  <button @click="changeValue">改变值</button>
  {{form}}
</div>

 new Vue({
    el: '#wrap',
    data:{
      form: '这是form的值',
      test: '<strong>我是粗体</strong>',
    },
    methods:{
      changeValue(){
        console.log(this.form)
        this.form = '值被我改变了，气不气？'
      }
    }
  })

  class Vue{
    constructor(){}
    proxyData(){}
    observer(){}
    compile(){}
    compileText(){}
  }
  class Watcher{
    constructor(){}
    update(){}
  }

  class Vue{
    constructor(options = {}){
      this.$el = document.querySelector(options.el);
      let data = this.data = options.data; 
      // 代理data，使其能直接this.xxx的方式访问data，正常的话需要this.data.xxx
      Object.keys(data).forEach((key)=> {
        this.proxyData(key);
      });
      this.methods = options.methods // 事件方法
      this.watcherTask = {}; // 需要监听的任务列表
      this.observer(data); // 初始化劫持监听所有数据
      this.compile(this.$el); // 解析dom
    }
  }

class Vue{
    constructor(options = {}){
      ......
    }
    proxyData(key){
      let that = this;
      Object.defineProperty(that, key, {
        configurable: false,
        enumerable: true,
        get () {
          return that.data[key];
        },
        set (newVal) {
          that.data[key] = newVal;
        }
      });
    }
  }

class Vue{
    constructor(options = {}){
      ......
    }
    proxyData(key){
      ......
    }
    observer(data){
      let that = this
      Object.keys(data).forEach(key=>{
        let value = data[key]
        this.watcherTask[key] = []
        Object.defineProperty(data,key,{
          configurable: false,
          enumerable: true,
          get(){
            return value
          },
          set(newValue){
            if(newValue !== value){
              value = newValue
              that.watcherTask[key].forEach(task => {
                task.update()
              })
            }
          }
        })
      })
    }
  }

  set(newValue){
    if(newValue !== value){
      value = newValue
      // 批量更新视图
      that.watcherTask[key].forEach(task => {
        task.update()
      })
    }
  }       

class Vue{
    constructor(options = {}){
      ......
    }
    proxyData(key){
      ......
    }
    observer(data){
      ......
    }
    compile(el){
      var nodes = el.childNodes;
      for (let i = 0; i < nodes.length; i++) {
        const node = nodes[i];
        if(node.nodeType === 3){
          var text = node.textContent.trim();
          if (!text) continue;
          this.compileText(node,'textContent')        
        }else if(node.nodeType === 1){
          if(node.childNodes.length > 0){
            this.compile(node)
          }
          if(node.hasAttribute('v-model') && (node.tagName === 'INPUT' || node.tagName === 'TEXTAREA')){
            node.addEventListener('input',(()=>{
              let attrVal = node.getAttribute('v-model')
              this.watcherTask[attrVal].push(new Watcher(node,this,attrVal,'value'))
              node.removeAttribute('v-model')
              return () => {
                this.data[attrVal] = node.value
              }
            })())
          }
          if(node.hasAttribute('v-html')){
            let attrVal = node.getAttribute('v-html');
            this.watcherTask[attrVal].push(new Watcher(node,this,attrVal,'innerHTML'))
            node.removeAttribute('v-html')
          }
          this.compileText(node,'innerHTML')
          if(node.hasAttribute('@click')){
            let attrVal = node.getAttribute('@click')
            node.removeAttribute('@click')
            node.addEventListener('click',e => {
              this.methods[attrVal] && this.methods[attrVal].bind(this)()
            })
          }
        }
      }
    },
    compileText(node,type){
      let reg = /\{\{(.*?)\}\}/g, txt = node.textContent;
      if(reg.test(txt)){
        node.textContent = txt.replace(reg,(matched,value)=>{
          let tpl = this.watcherTask[value] || []
          tpl.push(new Watcher(node,this,value,type))
          if(value.split('.').length > 1){
            let v = null
            value.split('.').forEach((val,i)=>{
              v = !v ? this[val] : v[val]
            })
            return v
          }else{
            return this[value]
          }
        })
      }
    }
  }

if(node.hasAttribute('v-html')){
  let attrVal = node.getAttribute('v-html');
  this.watcherTask[attrVal].push(new Watcher(node,this,attrVal,'innerHTML'))
  node.removeAttribute('v-html')
}

that.watcherTask[key].forEach(task => {
  task.update()
})

class Watcher{
  constructor(el,vm,value,type){
    this.el = el;
    this.vm = vm;
    this.value = value;
    this.type = type;
    this.update()
  }
  update(){
    this.el[this.type] = this.vm.data[this.value]
  }
}