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When no value is provided to the roll input field an alert is produced by the empty() function but this empty value is still passed to retrive.php. So how can I stop this from happening and only pass the value to retrive.php when some input value is provided?
<html>
<head>
<title>STUDENT FORM</title>
<script type="text/javascript">
function empty()
{
var x;
x = document.getElementById("roll-input").value;
if (x == "")
{
alert("Enter a Valid Roll Number");
};
}
</script>
</head>
<body >
<h1 align="center">student details</h1>
<div id="input">
<form action='retrive.php' method='get'>
<fieldset>
<legend>Get Details</legend>
<dl>
<dt><label for="roll-input">Enter Roll Number</label></dt>
<dd><input type="text" name="roll" id="roll-input"><dd>
<input type="submit" value="submit" onClick="empty()" />
</dl>
</fieldset>
</form>
</div>
</body>
</html>
410
If you're posting code, you need to precede it with a line containing only three backticks ``` and end it with a line contining only three backticks. Until someone uses it with JavaScript turned off!
We use the preventDefault() method with this event to prevent the default action of the form, that is prevent the form from submitting.
How do I stop a form from submitting in HTML? The simplest solution to prevent the form submission is to return false on submit event handler defined using the onsubmit property in the HTML <form> element.
You need to return false to cancel the submit.
function empty() {
var x;
x = document.getElementById("roll-input").value;
if (x == "") {
alert("Enter a Valid Roll Number");
return false;
};
}
and
<input type="submit" value="submit" onClick="return empty()" />
jsFiddle example
76
How about using the required attribute?
<input id="Name" name="Name" class="form-control" placeholder="Enter name" type="text" required/>
Only works in html5 though.
42
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