vue响应式原理实现

<input type="text" id="input">
<p id="showText"></p>

<script>
    var input = document.querySelector('#input')
    var showText = document.querySelector('#showText')

    var obj = {}

    Object.defineProperty(obj, 'something', {
        get: function() {
            console.log('get')
        },
        set: function(val) {
            showText.innerText = val;
            console.log(val)
        }
    })

    input.addEventListener('keyup', function(event) {
        obj.something = event.target.value
    })
</script>