As we mentioned in the previous section, verify whether the content of the form is empty. If it is empty, we will give a prompt message
Then let's look at how to remove the prompt message when entering content in the form text box or text field.
First of all, let’s think about the input content in the text box. This will trigger the keyboard event.
The code is as follows:
//When the text box of the user name triggers the keyboard event, prompt Information removal
Document.getElementById('name').onkeyup=function(){
Document.getElementById('sp').innerHTML = " ";
}
//When The password box trigger the keyboard event, prompt information to remove
DOCUMENT.GetelementByid ('PWD'). Onkeyup = Function () {
DOCUMENT.GetelementByid ('SP1'). }
// When the text box of the mailbox trigger the keyboard event, the prompt information removes
DOCumement.GelementByid ('SP2'). Ml = " ", sp3').innerHTML = " ";
}
The complete code is as follows:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style type="text/css">
*{margin:0;padding:0;}
#div{width:410px;height:400px;background:#46a3ff;padding-left:16px;
padding-top:20px;}
input{
outline:none;
box-sizing:border-box;padding-left:15px;}
textarea{
outline:none;resize : none;
box-sizing:border-box;padding-left:15px;padding-top:5px;}
.name{width:200px;height:30px;margin-left:8px;border:1px solid #ffc1e0;border-radius:8px;}
.pwd{width:200px;height:30px;
margin-left:8px;border:1px solid #ffc1e0;border-radius:8px;}
.email{width:200px;height:30px;margin-left:8px;border:1px solid #ffc1e0;border-radius:8px;}
.txt{
width:280px;height:70px;margin-left:8px;border:1px solid #ffc1e0;border-radius:8px;}
.sub{width:100px;height:30px;padding-left:0px;
border:none;
border-radius:5px;background:#ffd0ff;}
.sub:hover{background:#ffaad5;}
.div{
width:200px;height:30px;margin:0 auto;box-sizing:border-box;padding-left:45px;padding-top:5px;color:#8600ff;font-weight:bold;}
</style>
</head>
<body>
<div id="div">
<form>
<label>用户名:</label>
<input type="text" class="name" id="name">
<div id="sp" class="div"></div>
<label>密 码:</label>
<input type="password" class="pwd" id="pwd">
<div id="sp1" class="div"></div>
<label>邮 箱:</label>
<input type="text" class="email" id="email">
<div id="sp2" class="div"></div>
<label>爱 好:</label>
<textarea rows="5" cols="40" class="txt" id="txt"></textarea>
<div id="sp3" class="div"></div>
<input type="button" class="sub" value="注册" id="sub">
</form>
</div>
<script type="text/javascript">
var sub = document.getElementById('sub');
sub.onclick=function(){
//验证用户名是否为空,如果为空，给出提示信息
var val = document.getElementById('name').value;
if(val == ""){
document.getElementById("sp").innerHTML = "请输入用户名！";
}
//验证密码是否为空，为空则给出提示信息
var val1 = document.getElementById('pwd').value;
if(val1 == ""){
document.getElementById("sp1").innerHTML = "请输入密码！";
}
//验证邮箱是否为空
var val2 = document.getElementById('email').value;
if(val2 == ""){
document.getElementById("sp2").innerHTML = "请输入邮箱！";
}
//验证内容是否为空
var val3 = document.getElementById('txt').value;
if(val3 == ""){
document.getElementById("sp3").innerHTML = "请输入内容！";
}
}
//当用户名的文本框触发键盘事件，提示信息去除
document.getElementById('name').onkeyup=function(){
document.getElementById('sp').innerHTML = " ";
}
//当密码框触发键盘事件，提示信息去除
document.getElementById('pwd').onkeyup=function(){
document.getElementById('sp1').innerHTML = " ";
}
//当邮箱文本框触发键盘事件，提示信息去除
document.getElementById('email').onkeyup=function(){
document.getElementById('sp2').innerHTML = " ";
}
//当文本域触发键盘事件，提示信息去除
document.getElementById('txt').onkeyup=function(){
document.getElementById('sp3').innerHTML = " ";
}
</script>
</body>
</html>