Vue实现双向数据绑定

var data = {
 value: 'hello world!'
}
var bindValue;
//确定绑定的元素
var bindelems = [document.getElementById('p'), document.getElementById('input')];
//修改绑定元素的值的方法
var command = {
 text: function(str) {
 this.innerHTML = str;
 },
 value: function(str) {
 this.value = str;
 }
};
//遍历绑定元素修改其值
var scan = function() {
 console.log('in scan');
 for(var i = 0; i < bindelems.length; i++) {
 var elem = bindelems[i];
 console.log('elem',elem);
 for(var j = 0; j < elem.attributes.length; j++) {
 var attr = elem.attributes[j];
 if(attr.nodeName.indexOf('q-')>=0) {
 command[attr.nodeName.slice(2)].call(elem, data[attr.nodeValue]);
 }
 }
 }
}
//设置劫持
var defineGetAndSet = function(obj, propname) {
 Object.defineProperty(obj, propname, {
 get: function() {
 return bindValue;
 },
 set: function(value){
 bindValue = value;
 scan();
 },
 enumerable: true,
 configurable: true
 })
} 
//一开始先初始化，使所有绑定的元素值为初始值
scan();
//设置需要被劫持的元素
defineGetAndSet(data, 'value');
//监听UI变化
bindelems[1].addEventListener('keyup', function(e) {
 data.value = e.target.value;
});
setTimeout(function() {
 data.value = 'change';
}, 1000);