<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
}
.search {
position: relative;
width: 178px;
margin: 100px;
}
.con {
display: none;
position: absolute;
top: -40px;
width: 171px;
border: 1px solid rgba(0, 0, 0, .2);
box-shadow: 0 2px 4px rgba(0, 0, 0, .2);
padding: 5px 0;
font-size: 18px;
line-height: 20px;
color: #333;
}
.con::before {
content: \'\';
width: 0;
height: 0;
position: absolute;
top: 28px;
left: 18px;
border: 8px solid #000;
border-style: solid dashed dashed;
border-color: #fff transparent transparent;
}
</style>
</head>
<body>
<div class="search">
<div class="con">123</div>
<input type="text" placeholder="请输入您的快递单号" class="jd">
</div>
<script>
var con = document.querySelector(\'.con\');
var jd_input = document.querySelector(\'.jd\');
jd_input.addEventListener(\'keyup\', function() {
if (this.value == \'\') {
con.style.display = \'none\';
} else {
con.style.display = \'block\';
con.innerText = this.value;
}
})
// 失去焦点 就隐藏盒子
jd_input.addEventListener(\'blur\', function() {
con.style.display = \'none\';
})
// 获得焦点 就显示盒子
jd_input.addEventListener(\'focus\', function() {
if (this.value != \'\') {
con.style.display = \'block\';
}
})
</script>
</body>
</html>