html form hidden variable not showing in php

Question

I have a HTML form that submits to PHP. There is an onChange event on a drop down box that calls a JavaScript function which writes a hidden variable into the form. This additional hidden variable doesnt show up in PHP though, why is this?

So;

<script language="JavaScript">
function change() {
  document.getElementById("myDiv").innerHTML="<input type=\"hidden\" name=\"blah\" value=\"1\"/>";
  return;
}
</script>

<form method="post" action="test.php" />
<select name="cid" id="cid" onChange="change();">
<option value="lala">lala</option>
</select>
<div id="myDiv"></div>
</form>

PHP doesn't see $_POST['blah']?

It's hard to see, where the error lies. Please paste the code where the onChange function is called. And I can't see any submit Button which submits the form. And by the way, it is: <script type="text/javascript"> — Sarah West
– Sarah West, Commented Aug 22, 2011 at 13:22
OK, I have added more code to show whats going on, its a long form so I tried to cut some of the other crap out. — Baldrick
– Baldrick, Commented Aug 22, 2011 at 14:09

Rijk · Accepted Answer · 2011-08-22 13:18:11Z

3

A more logical solution anyway would be to just add the hidden field to your form, and set the value to 1 in the onChange function.

answered Aug 22, 2011 at 13:18

Rijk

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1 Comment

Baldrick Over a year ago

I didnt do it this way round because I didnt want the variable to be there if the drop down box wasnt changed but this way works, so thanks :D

Michael · Accepted Answer · 2011-08-22 13:17:14Z

2

You must have been setup something wrong, it dose work fine when I test that. Are you sure you call the method before you submit the form ?

answered Aug 22, 2011 at 13:17

Michael

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Comments

Stefan · Accepted Answer · 2011-08-22 13:18:11Z

2

I can´t see you executing your change() function.

answered Aug 22, 2011 at 13:18

Stefan

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2 Comments

Baldrick Over a year ago

As I said, the function is called by the onChange event of a drop down box, I can see the code change in the page.

Rijk Over a year ago

I think adding the field to the DOM doesn't make the browser implicitly add it to the form it has in memory. As stated in my answer; it would make more sense to have the field in the form from the start, and set the value using JS.

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