最近研究Vue的底层原理，写了一个简化版的Vue，可以在支持IE6、IE7、IE8等低端浏览器运行。由于低端浏览器不支持对象属性定义，所以设置属性不支持直接赋值，需要调用虚拟机实例的set方法。目前只实现了基础的方法，后续继续完善！
index.html
<!DOCTYPE html>
<html>
<head>
<title>简化版Vue</title>
<script>
window.onerror=function(){
return true;
}
</script>
</head>
<body>
<hr />
<div id="simpleVue">
<button v-on:click="copy">戳我</button>
<div>
<textarea v-model="name"></textarea>
<div v-text="name"></div>
</div>
<div>
<select v-model="name">
<option value="name1" selected>name1</option>
<option value="name2">name2</option>
<option value="name3">name3</option>
</select>
</div>
<hr>
<button v-on:click="show">显示/隐藏</button>
<div v-if="isShow">
<input type="text" style="width: 300px" v-model="webSite">
<div v-text="webSite"></div>
</div>
</div>
<script src="vmm.js"></script>
<script>
var vm = new VMM({
el: '#simpleVue',
data: {
name: '测试',
webSite: 'https://github.com/steezer',
isShow: true
},
methods: {
copy: function(){
vm.set('name', this.name +'测试');
},
show: function(){
vm.set('isShow', !this.isShow);
}
}
});
</script>
</body> </html>
vmm.js
function VMM(options){
/**
* 订阅器构造 用来接收属性值的相关数据的变化通知 从而更新视图
*
* @param {Object} vm 虚拟机对象
* @param {HTMLElement} el Node节点
* @param {String} attr 属性名称
* @param {Object} val 属性值
*/
function Watcher(vm, el, attr, val){
this.vm = vm;
this.el = el;
this.attr = attr;
this.val = val;
/**
* 将收到的新的数据更新在视图中
*/
this.update = function() {
if (this.vm.$data[this.val] === true) {
this.el.style.display = 'block';
} else if (this.vm.$data[this.val] === false) {
this.el.style.display = 'none';
} else {
this.el[this.attr] = this.vm.$data[this.val];
}
}
// 初始化订阅器时更新一下视图
this.update();
}
/**
* 获取对象
*
* @param {Object|String} id
* @returns Object
*/
function getElem(id){
if(typeof(id)=='object'){
return id;
}
var target=id+'',
prefix=target.substr(0,1),
target=target.substr(1);
if(prefix=='#'){
return document.getElementById(target);
}
if(prefix=='.'){
return document.getElementsByClassName(target);
}
return document.getElementsByTagName(target);
}
function getAttr(elem, name) {
var node = elem.getAttributeNode(name);
if (node && node.specified) {
return node.nodeValue;
} else {
return undefined;
}
}
function addEvent(node, type, handle){
if(document.addEventListener){
node.addEventListener(type, handle, false);
}else{
node.attachEvent('on'+type, function(){
handle.call(node, arguments);
});
};
}
this.$el = getElem(options.el);
this.$data = options.data;
this.$methods = options.methods;
this.oWatcherObj = {};
// 获取属性
this.get=function(key){
return this.$data[key];
}
// 设置属性
this.set=function(key, newVal){
var value=this.$data[key];
if (newVal !== value) {
this.$data[key] = newVal;
if(typeof(this.oWatcherObj[key])!="undefined"){
var watchers=this.oWatcherObj[key];
for(var i=0; i< watchers.length; i++){
watchers[i].update();
}
}
}
}
/**
* 节点DOM解析器
*/
this.compile=function(el) {
var nodes = el.children,
$this=this,
addWatcher=function(node, attr, val){
if(typeof($this.oWatcherObj[val])=='undefined'){
$this.oWatcherObj[val]=[];
}
$this.oWatcherObj[val].push(new Watcher($this, node, attr, val));
};
// 迭代同级所有节点
var values=[];
for(var k in el){
values.push(k)
}
for (var i = 0; i < nodes.length; i++) {
var node = nodes[i],val;
if (node.children.length > 0) {
this.compile(node); // 递归所有子节点
}
// 点击事件
val=getAttr(node, 'v-on:click');
if (val) {
if(typeof($this.$methods[val])=="function"){
addEvent(node, 'click', (function(val){
return function(e){
$this.$methods[val].call($this.$data, e);
}
})(val));
}
}
// IF指令
val=getAttr(node, 'v-if');
if (val) {
addWatcher(node, "", val);
}
// Model
val=getAttr(node, 'v-model');
if (val) {
var event=node.tagName.match(/select/i) ? 'change' :
('oninput' in node ? 'input' : 'propertychange');
addWatcher(node, "value", val);
addEvent(node, event, (function(i, val){
return function(e){
$this.set(val, nodes[i].value);
}
})(i, val));
}
// Text
val=getAttr(node, 'v-text');
if (val) {
addWatcher(node, "innerText", val);
}
// Html
val=getAttr(node, 'v-html');
if (val) {
addWatcher(node, "innerHTML", val);
}
}
}
// 节点解析
this.compile(this.$el);
}