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如果留空,如何在相应的输入字段下打印错误消息,填写时必须删除错误消息,如何进一步进行我之前没有使用 javascript 进行验证。
脚本代码
function validateForm() {
var a = document.forms["student_reg"]["name"].value;
if (a == null || a == "") {
alert("Name must be filled out");
return false;
}
var b = document.forms["student_reg"]["email"].value;
if (b == null || b == "") {
alert("Email must be filled out");
return false;
}
var c = document.forms["student_reg"]["username"].value;
if (c == null || c == "") {
alert("Username must be filled out");
return false;
}
var d = document.forms["student_reg"]["password"].value;
if (d == null || d == "") {
alert("Password must be filled out");
return false;
}
var e = document.forms["student_reg"]["roll_no"].value;
if (e == null || e == "") {
alert("Roll no must be filled out");
return false;
}
}
html代码在这里
<body>
<a href="login.php">Login</a>
<form name="student_reg" method="POST" action="" onsubmit="return validateForm()">
<p>NAME:</p>
<input type="text" name="name" value="" >
<span class="error"><p id="name_error"></p></span>
<p>EMAIL:</p>
<input type="text" name="email" value="" >
<span class="error"><p id="email_error"></p></span>
<p>USERNAME:</p>
<input type="text" name="username" value="" >
<span class="error"><p id="username_error"></p></span>
<p>PASSWORD:</p>
<input type="password" name="password" value="" >
<span class="error"><p id="password_error"></p></span>
<p>ROLL NO:</p>
<input type="number" name="roll_no" value="" >
<span class="error"><p id="roll_no_error"></p></span>
<br/>
<br/>
<br/>
<input type="submit" name="submit" value="submit">
</form>
</body>