Set hidden field value using Javascript; use PHP post method to send the data

Question

I need to get the user's screen resolution and save it my database.

What I'm doing is this: I have a Javascript function called with that gets the info and passes the value to a hidden form field. This is the function:

<script type="text/javascript">

function getUserData(){

var s_width=screen.width
var s_height=screen.height
document.getElementById('screen_width').value=s_width
document.getElementById('screen_height').value=s_height

}

</script>

And the form:

<form name="login" id="login" action="memberlogin.php" method="post">
<input type="hidden" id="screen_width" name="screen_width">
<input type="hidden" id="screen_height" name="screen_height">
<table style="margin-top:9px;">
<tr><td width="200px"><input type="text" name="username" style="width:100%"/></td></tr>
<tr><td width="200px"><input type="password" name="password" style="width:100%"/></td></tr>
<tr><td><input type="submit" name="submit" value="Log In" /></td></tr>
</table>
</form>

The form submits to the same page. When I click 'submit' and try to echo the value of $_POST['screen_width'] and $_POST['screen_height'], nothing happens. But when I re-submit it, the values are there. Can someone tell me what am I doing wrong? If you have an alternative solution, it would be equally appreciated.

How is the PHP code relevant here? All PHP does at the moment is: echo $_POST['screen_width']; — robert
– robert, Commented Jan 5, 2012 at 11:16
amccausl, the function is called inside the <body> tag with <body onLoad="getUserData()"> — robert
– robert, Commented Jan 5, 2012 at 11:17

maialithar · Accepted Answer · 2012-01-05 14:19:51Z

1

have you checked firebug's output? maybe there are some errors? try alert sth in your function, maybe it isn't called after initial page load? try putting function call in submit button's onClick or form's onSubmit event.

answered Jan 5, 2012 at 14:19

maialithar

3,1245 gold badges30 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

robert · Accepted Answer · 2012-01-09 15:31:13Z

0

Solved it myself, it was just a matter of calling the function after loading the element.

answered Jan 9, 2012 at 15:31

robert

8413 gold badges16 silver badges28 bronze badges

Collectives™ on Stack Overflow

Set hidden field value using Javascript; use PHP post method to send the data

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related