题解 | #单向绑定#
单向绑定
https://www.nowcoder.com/practice/728b83e2b9b948dbababcc4a494eefc3
不支持 const / let，要用 var，莫非在线解释器/编译器用的是 ES5 语法？！
<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8>
</head>
<body>
<input id="input" type="text" />
<span id="span"></span>
<script type="text/javascript">
// 补全代码
var input = document.getElementById('input');
var span = document.getElementById('span');
input.onchange = (e) => {
span.innerText = input.value
}
</script>
</body>
</html>
