html部分
<div id="app"> <input type="text" id="txt"> <p id="show"></p> </div>js部分
<script> var obj = {} Object.defineProperty(obj, 'txt', { get: function() { return obj }, set: function(newValue) { document.getElementById('txt').value = newValue document.getElementById('show').innerHTML = newValue } }) document.addEventListener('keyup', function(e) { obj.txt = e.target.value }) </script>