A brief analysis of the two-way binding principle of complie data in Vue (detailed code explanation)-Vue.js-php.cn

A brief analysis of the two-way binding principle of complie data in Vue (detailed code explanation)

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Release： 2021-08-24 10:20:33

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之前的文章《一文了解vue中watcher数据双向绑定原理（附代码）》中，给大家介绍了解了vue中complie数据双向绑定原理。下面本篇文章给大家了解vue中complie数据双向绑定原理，伙伴们过来看看吧。

A brief analysis of the two-way binding principle of complie data in Vue (detailed code explanation)

vue数据双向绑定原理，和简单的实现，本文将实现mvvm的模板指令解析器

A brief analysis of the two-way binding principle of complie data in Vue (detailed code explanation)

1）vue数据双向绑定原理-observer

2）vue数据双向绑定原理-wather

3）vue数据双向绑定原理-解析器 Complie

vue数据双向绑定原理，和简单的实现，本文将实现mvvm的模板指令解析器

上一步实现了简单数据绑定，最后实现解析器，来解析v-model,v-on:click等指令，和{{}}模板数据。解析器Compile实现步骤：

解析模板指令，并替换模板数据，初始化视图
将模板指令对应的节点绑定对应的更新函数，初始化相应的订阅器

为了解析模板，首先需要获取到dom元素，然后对含有dom元素上含有指令的节点进行处理，因此这个环节需要对dom操作比较频繁，所有可以先建一个fragment片段，将需要解析的dom节点存入fragment片段里再进行处理：

function node2Fragment(el) {
  var fragment = document.createDocumentFragment(),
    child;
  // 将原生节点拷贝到fragment
  while ((child = el.firstChild)) {
    fragment.appendChild(child);
  }

  return fragment;
}

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接下来渲染'{{}}'模板

//Compile
function Compile(el, vm) {
  this.$vm = vm;
  this.$el = this.isElementNode(el) ? el : document.querySelector(el);
  if (this.$el) {
    this.$fragment = this.node2Fragment(this.$el);
    this.init();
    this.$el.appendChild(this.$fragment);
  }
}

Compile.prototype = {
  init: function () {
    this.compileElement(this.$fragment);
  },

  node2Fragment: function (el) {
    //...
  },

  //编译模板
  compileElement: function (el) {
    var childNodes = el.childNodes,
      self = this;
    [].slice.call(childNodes).forEach(function (node) {
      var text = node.textContent;
      var reg = /{{(.*)}}/; //表达式文本
      //按元素节点方式编译
      if (self.isElementNode(node)) {
        self.compile(node);
      } else if (self.isTextNode(node) && reg.test(text)) {
        self.compileText(node, RegExp.$1);
      }
      //遍历编译子节点
      if (node.childNodes && node.childNodes.length) {
        self.compileElement(node);
      }
    });
  },

  isElementNode: function (node) {
    return node.nodeType == 1;
  },

  isTextNode: function (node) {
    return node.nodeType == 3;
  },

  compileText: function (node, exp) {
    var self = this;
    var initText = this.$vm[exp];
    this.updateText(node, initText);
    new Watcher(this.$vm, exp, function (value) {
      self.updateText(node, value);
    });
  },

  updateText: function (node, value) {
    node.textContent = typeof value == "undefined" ? "" : value;
  },
};

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处理解析指令对相关指令进行函数绑定。

Compile.prototype = {

  ......
  isDirective: function(attr) {
    return attr.indexOf(&#39;v-&#39;) == 0;
  },

  isEventDirective: function(dir) {
    return dir.indexOf(&#39;on:&#39;) === 0;
  },

  //处理v-指令
  compile: function(node) {

    var nodeAttrs = node.attributes,
      self = this;
    [].slice.call(nodeAttrs).forEach(function(attr) {
      // 规定：指令以 v-xxx 命名
      // 如 <span v-text="content"></span> 中指令为 v-text
      var attrName = attr.name; // v-text
      if (self.isDirective(attrName)) {
        var exp = attr.value; // content
        var dir = attrName.substring(2); // text
        if (self.isEventDirective(dir)) {
          // 事件指令, 如 v-on:click
          self.compileEvent(node, self.$vm, exp, dir);
        } else {
          // 普通指令如:v-model, v-html, 当前只处理v-model
          self.compileModel(node, self.$vm, exp, dir);
        }
        //处理完毕要干掉 v-on:, v-model 等元素属性
        node.removeAttribute(attrName)
      }
    });

  },

  compileEvent: function(node, vm, exp, dir) {

    var eventType = dir.split(&#39;:&#39;)[1];
    var cb = vm.$options.methods && vm.$options.methods[exp];
    if (eventType && cb) {
      node.addEventListener(eventType, cb.bind(vm), false);
    }

  },

  compileModel: function(node, vm, exp, dir) {

    var self = this;
    var val = this.$vm[exp];
    this.updaterModel(node, val);
    new Watcher(this.$vm, exp, function(value) {
      self.updaterModel(node, value);
    });
    node.addEventListener(&#39;input&#39;, function(e) {
      var newValue = e.target.value;
      if (val === newValue) {
        return;
      }
      self.$vm[exp] = newValue;
      val = newValue;
    });

  },

  updaterModel: function(node, value, oldValue) {
    node.value = typeof value == &#39;undefined&#39; ? &#39;&#39; : value;
  },

}

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最后再关联起来

function Vue(options) {
  .....
  observe(this.data, this);
  this.$compile = new Compile(options.el || document.body, this)
  return this;

}

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来尝试下效果

<!--html-->
<div id="app">
  <h2>{{name}}</h2>
  <input v-model="name" />
  <h1>{{name}}</h1>
  <button v-on:click="test">click here!</button>
</div>
<script>
  new Vue({
    el: "#app",
    data: {
      name: "chuchur",
      age: 29,
    },
    methods: {
      test() {
        this.name = "My name is chuchur";
      },
    },
  });
</script>

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OK. 基本完善了

推荐学习：vue.js教程

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