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<!DOCTYPE html> <html> <body> <form name="myForm" action="demo_form.php" onsubmit="return validateForm()" method="post"> First name: <input type="text" name="fname"> <input type="submit" value="Submit"> </form> <script> function validateForm() { var x=document.forms["myForm"]["fname"].value if (x==null || x=="") { alert("First name must be filled out"); return false; } } </script> </body> </html>
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