How to validate a form in JavaScript

<html>
<head>
<title>Form Validation With JavaScript</title>

<script>
function validateForm() 
{
    var nm = document.forms["formname"]["firstname"].value;
    
    if (nm == "" || nm == null) 
    {
        alert("Please write a name");
        return false;
    }
}
</script>

</head>
<body>
  <form name="formname" action="add-user.php" onsubmit="return validateForm();" method="post">
    Name: <input type="text" name="firstname">
    <input type="submit" value="Submit">
</form>
</body>
</html>

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answered Jun 28, 2015 by avibootz

<html>
<head>
<title>Form Validation With JavaScript</title>

<script>
function validateForm() 
{
    var nm = document.getElementById("firstname-id").value;
    
    if (nm == "" || nm == null) 
    {
        alert("Please write a name");
        return false;
    }
}
</script>

</head>
<body>
  <form name="formname" action="add-user.php" onsubmit="return validateForm()" method="post">
    Name: <input id="firstname-id" type="text" name="firstname">
    <input type="submit" value="Submit">
</form>
</body>
</html>

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answered Jun 28, 2015 by avibootz

<!-- test.html -->

<html>
<head>
<title>Form Validation With JavaScript</title>
<script type="text/javascript" src="test.js"></script> 
</head>

<body>
  <form name="formname" action="add-user.php" onsubmit="return validateForm()" method="post">
    Name: <input id="firstname-id" type="text" name="firstname">
    <input type="submit" value="Submit">
</form>
</body>
</html>

// test.js

function validateForm() 
{
    var nm = document.getElementById("firstname-id").value;
    
    if (nm == null || nm == "") 
    {
        alert("Please write a name");
        
        return false;
    }
}

70+ SQL courses for beginners and professionals

answered Jun 28, 2015 by avibootz

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How to validate a form in JavaScript

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