vue底层原理之双向数据绑定,用js简单实现

//html

<input id="one" type="text" placeholder="请输入值">
<p>
    当前输入的值:
    <span id="two">--</span>
</p>

 

//js

var oOne = document.getElementById('one');
var oTwo = document.getElementById('two');
var newValue = {};
Object.defineProperty(newValue, 'msg', {
    // 设置 obj.msg  当obj.msg反生改变时set方法将会被调用
    set: function (newVal) {
        // 当obj.msg被赋值时 同时设置给 input/span
        oOne.value = newVal
        oTwo.innerText = newVal
    }
});

oOne.addEventListener('keyup', function (event) {
    newValue.msg = event.target.value
})