JavaScript基础学习 模拟京东查询快递单号
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=devcie-width,initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
.box {
height: 50px;
width: 500px;
background-color: pink;
font-size: 50px;
display: none;
}
</style>
</head>
<body>
<div>
<div class="box"></div><br>
<input type="text" placeholder="请输入你的快递单号" id="jd">
</div>
<script>
var input = document.querySelector('input');
var box = document.querySelector('.box');
input.addEventListener('keyup', function() {
if (this.value == '') {
box.style.display = 'none';
} else {
box.style.display = 'block';
box.innerHTML = this.value;
}
})
// 当我们失去焦点时，就隐藏输入框上方的盒子
input.addEventListener('blur', function() {
box.style.display = 'none';
})
// 当我们获得焦点时，就显示输入框上方的盒子
input.addEventListener('focus', function() {
if (this.value == '') {
box.style.display = 'none';
} else {
box.style.display = 'block';
}
})
</script>
</body>
</html>
