手写vue双向绑定数据

来一张原理图：

实现思路：

　　（1）绑定data 种的数据，为每个数据添加指令。通过Object,defineProperty() 来通知属性是否更改

　　（2） 找到每个DOM节点的指令。绑定事件。并绑定watcher

　　（3）  实现DOM事件改变之后， 响应data数据，实现视图更新

<!DocType>
<html>
  <title>vue 的双向绑定事件</title>
  <body id="app">
    <input type="text" v-model="number"/>
    <span v-bind="number"></span>
    <input type="text" v-model="age"/>
    <span v-bind="age"></span>
  </body>
   
<script>
  function Vue (options) {
     this._init(options);
  }
  
  Vue.prototype._init = function (options) {
    this.$data = options.data;
    this.$methods = options.data.methods;
    this.$el = document.querySelector(options.el);
    this.$methods = options.methods;
    this.$key = '';
    
    this._binding = {};
    
    // 观测数据
    this._observer(this.$data);
    
    this._complie(this.$el);
    
    // this._test(this.$data);
  }
  
  // 观测数据
  Vue.prototype._observer = function (obj) {
    var value;
    let _this = this;
    for (key in obj) {
      if (obj.hasOwnProperty(key)) {
        this._binding[key] = {                                                                                                                                                          
          _directives: []
        };
        value = obj[key];
        if (typeof value === 'object') {
          this._observer(value);
        }
        Object.defineProperty(this.$data, key, {
          enumerable: true,
          configurable: true,
          get: function () {
            console.log(`获取${value}`, key);
            return value;
          },
          set: function (newVal) {
            console.log('key:', key, _this.$key);
            if (value !== newVal) {
              value = newVal;
              _this._binding[_this.$key]._directives.forEach(function (item, index) {
                item.update();
              })
            }
          }
        })
      }
    }
  }
  
  // 为DOM节点添加指令事件
  Vue.prototype._complie = function (root) {
    var _this = this;
    var nodes = root.children;
    for (var i = 0; i < nodes.length; i++) {
      var node = nodes[i];
      if (node.children.length) {
        this._complie(node);
      }

      if (node.hasAttribute('v-click')) {
        node.onclick = (function () {
          var attrVal = nodes[i].getAttribute('v-click');
          return _this.$methods[attrVal].bind(_this.$data);
        })();
      }

      if (node.hasAttribute('v-model') && (node.tagName == 'INPUT' || node.tagName == 'TEXTAREA')) {
        node.addEventListener('input', (function(key) {
          var attrVal = node.getAttribute('v-model');
          _this._binding[attrVal]._directives.push(new Watcher(
            'input',
            node,
            _this,
            attrVal,
            'value'
          ))

          return function() {
            _this.$key = attrVal
            _this.$data[attrVal] =  nodes[key].value;
          }
        })(i));
      } 

      if (node.hasAttribute('v-bind')) {
        var attrVal = node.getAttribute('v-bind');
        _this._binding[attrVal]._directives.push(new Watcher(
          'text',
          node,
          _this,
          attrVal,
          'innerHTML'
        ))
      }
    }
  }
  
   function Watcher(name, el, vm, exp, attr) {
    this.name = name;         //指令名称，例如文本节点，该值设为"text"
    this.el = el;             //指令对应的DOM元素
    this.vm = vm;             //指令所属myVue实例
    this.exp = exp;           //指令对应的值，本例如"number"
    this.attr = attr;         //绑定的属性值，本例为"innerHTML"

    this.update();
  }
  
  // 更新数据
  Watcher.prototype.update = function () {
    this.el[this.attr] = this.vm.$data[this.exp];
  }
  
  
  // 测试
  Vue.prototype._test = function($data) {
     var a = $data.number;
     $data.number = 32;
  }
  
  window.onload = function () {
    var app = new Vue({
      el: '#app',
      data: {
         number: 12,
         age: 444
      },
      methods: {}
    })
  }

</script>
</html>

 

posted @ 2018-04-19 20:07  Animationer  阅读(3358)  评论(0)  编辑  收藏  举报