正在清除验证错误JavaScript

Question

我一直试图在用户成功输入并完成所需的验证规则后清除消息，但我似乎无法清除所有的验证错误，我确实四处查看并尝试了建议，但似乎没有奏效。我认为通过放置空的innerHTML字符串可能会像我所说的那样在的其他帖子中得到建议

<form action ="" method="POST">
<span id="tryErr"></span><br>
<input type="text" id="username" placeholder="Username"><br>
<span id="usernameErr"></span><br>
<input type="text" id="email" placeholder="Email address"><br>
<span id="emailErr"></span><br>
<input type="password" id="password" placeholder="Password"><br>
<span id="passwordErr"></span><br>
<input type="submit" value="Submit" onclick=" return confirmValidation();">
</form>    

JS-

<script type="text/javascript">      
function validateUsername(username, error){
var username = document.getElementById("username").value,
error = document.getElementById("usernameErr");
if(username == null || username==""){   
return error.innerHTML = "Username is required";
return false;
}
else if(!username.match(/^[0-9a-z]+$/) || username.length < 3){
return error.innerHTML = "Username must be alphanumeric and three characters long";
return false;
}
else{
return error.innerHTML = "";
return true;
}
}
function validatePassword(password, error){
var password = document.getElementById("password").value,
error = document.getElementById("passwordErr");
if(password == null || password==""){
return error.innerHTML = "Password is required";
return false;
}
else if(password.length < 7){
return error.innerHTML = "Password must be seven characters long";    
return false;
}
else{
return error.innerHTML = ""; 
return true;
}
}
function validateEmail(email, error){
var email = document.getElementById("email").value,
apos = email.indexOf("@"),
dotpos = email.lastIndexOf("."),
error = document.getElementById("emailErr");
if(email == null || email==""){
return error.innerHTML = "Email is required";
return false;
}
if (apos < 1  ||  dotpos-apos < 2 || dotpos == (email.length - 1)){
return error.innerHTML = "Please enter a valid email";
return false;
} 
else{
return error.innerHTML = "";
return true;
}
}

function confirmValidation(e){
event.preventDefault(e);    
if(!validateUsername()){
return false;
}
if(!validatePassword()){
return false;
}
if(!validateEmail()){
return false;
}
else{
//do something clever here
}
}
</script>

Answer 1

您应该对输入类型使用onchange事件。像

<input type="text" id="username" placeholder="Username " onchange="validateUsername()">