显示隐藏文本框内容
首先需要失去焦点onblur
和获得焦点onfocus
;
如果获取焦点,默认值设置为空;
当失去焦点时,且没输入值则把值改为默认值。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<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">
<script>
var text=document.querySelector('input');
text.onfocus=function(){
if(this.value==='手机'){
this.value='';
}
this.style.color='#333';
}
text.onblur=function(){
if(this.value===''){
this.value='手机';
this.style.color='#999';
}
}
</script>
</body>
</html>
密码验证问题
验证输入密码是否为6-16:
<body>
<div class=""register>
<input type="password" class="ipt" id="">
<p class="message">请输入6-16位密码</p>
</div>
<script>
var ipt=document.querySelector('.ipt');
var message=document.querySelector('.message');
ipt.onblur=function(){
if(this.value.length<6||this.value.length>16)
{
message.style.color='red';
message.innerHTML='你输错了';
}else{
message.innerHTML='你输对了';
}
}
</script>
</body>