<!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>
input {
color: #999;
}
</style>
</head>
<body>
<input type="text" value="手机" id="">
<script>
//1.获取元素
var text = document.querySelector('input');
//2.注册事件 获得焦点事件
text.onfocus = function() {
console.log('得到了焦点');
if(this.value === '手机'){
this.value = '';
}
this.style.color = '#333';
}
//3.注册事件 失去焦点 onbur
text.onblur = function() {
console.log('失去了焦点');
if(this.value != '');{
this.value = '手机';
}
this.style.color = '#999';
}
</script>
</body>
</html>