Friday, January 13, 2012

Why is the form not preventing submission?


I have a basic form that I am using as a dummy to test some JavaScript functionality. My goal is to click the submit button and have submission paused until a javascript function is executed, then submit the form after that. the code I currently have is below, but the submission of the form is not prevented, and the hidden field's value is never set. can someone explain why this is happening?



NOTE I am aware of a jQuery method of performing the same functionality. I am specifically trying to solve this problem without using jQuery. If your only answer is "jQuery is better", please do not bother.




<html>
<head>
<script type="text/javascript">
function test(){
document.getElementById("hidden").value="hidden";

var queryString = $('#decisionform').formSerialize();
alert(queryString);

document.getElementById("form").submit();
}
</script>
</head>

<body>

<?php
if ($_POST){
foreach ($_POST as $key=>$value){
echo "<b>$key</b> $value<br>";
}
}
?>

<form action="hello.php" method="post" id="form">
<input name="first" type="text" />
<input name="second" type="text" />
<input name="third" type="text" />
<input name="hidden" type="hidden" />
<input name="submit" type="submit" value="Submit" onclick="test();return false;" />
</form>

</body>
</html>

6 comments:

  1. You don't have an element with the id hidden so document.getElementById("hidden").value="hidden"; will throw an error as you can't set properties on undefined. The script will stop running and never reach return false so the form will submit as normal.

    ReplyDelete
  2. try <form action="hello.php" method="post" id="form" onsubmit="test(); return false;">

    to prevent a submit, you actually need to have a return false, in the onsubmit even of the form itself

    along with not having an id on the hidden field.

    ReplyDelete
  3. <input name="submit" type="submit" value="Submit" onclick="test();return false;" />


    use a regular button in this case because your function is performing the submit.

    <input name="submit" type="button" value="Submit" onclick="test()" />

    ReplyDelete
  4. You're missing the id attribute from your input element. Modify <input name="hidden" type="hidden" /> to <input name="hidden" type="hidden" id="hidden" />.

    ReplyDelete
  5. You can use

    onclick="return test()"


    and just return false at the end of the function.

    ReplyDelete
  6. Add id="hidden" to your input, like this:

    <input name="hidden" type="hidden" id="hidden" />

    ReplyDelete