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I'm having a problem in passing variable from Javascript to PHP,
passing variables from PHP to Javascript is Easy
but is there a way to pass Variables from Javascript to PHP?

Here's the Situation
Think of this as the variables of the first select input
--2010
--2011
--2012

and

the Values of the second select group varies depending on the selected option
of the first select group
The values are:

2010
--AAA
--AAB
--AAC

2011
--ABA
--ABB
--ABC

2012
--ACA
--ACB
--ACC


say that the values are displayed by a conditional PHP function that
retrieves data from a Database

Here's What I Want to do:
When I Select One from the first select Group,
It will change the options of the second select group
of course, this happens via triggers when the first select group changes

I need to Retrieve the value of the first select group to filter the data
that will be displayed as the options of the second Group which comes from
a database and a PHP function is made to process it, thats why i need the value
of the first select group and use it as a parameter for the second select group.

The Problem:
i need to get the value of the first select group in PHP Varible
to make a PHP Function work.

Please Help!!!

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1  
There are lots of questions in the "Related" section on the right that answer this. – Jon Oct 2 '12 at 8:17
I think if there any, i wont be asking at the first place, well if you know where to find then answer this: – Lynyrd Salita Oct 2 '12 at 9:03

2 Answers

up vote 1 down vote

You can simply add it in as a url parameter in the ajax request that you send.

Consider your first field is like so:

<select id="field1">
    <option value="2010">2010</option>
    <option value="2011">2011</option>
    <option value="2012">2012</option>
</select>

Your javascript will be like so:

var ajaxUrl="http://myserver.com/getfield2.php?field1=" + document.getElementById("field1").value;

And then you will send the ajax request to ajaxUrl

In the php, you will get this value as 

$_GET["field1"]
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Good answer, just a comment: in your JS code, you have "-" instead of "=". – Shlomi Fish Oct 2 '12 at 8:21
whoops...new keyboard does that to me :P – Pranav Hosangadi Oct 2 '12 at 8:31
thnx for the answer but which is which? which one gous in the serverside code and which is the script code in the main page? – Lynyrd Salita Oct 2 '12 at 8:49
@LynyrdSalita: In your php code, which is server-side, you'll get the value as $_GET["field1"]....in your main page, you'll put in the javascript code. I'm assuming your select element has the id attribute set to "field1". If it is different, change the "field1" in document.getElementById("field1") to your actual id – Pranav Hosangadi Oct 2 '12 at 9:02
Also I'm assuming you have basic knowledge of how to find your way in javascript, and that you already know how to listen to the dropdown value being changed – Pranav Hosangadi Oct 2 '12 at 9:05
up vote 0 down vote

Like said above, your fields are

<select id="field1">
    <option value="2010">2010</option>
    <option value="2011">2011</option>
    <option value="2012">2012</option>
</select>

Use jQuery to perform an AJAX call to your script. Something like that

$("#field1").change(function(){
  var value = $(this).val();
  $.post('script.php', {
    phpvar: value
  }, function(){
    //this is callback, render your second field here, with the responce of php script
  });
});

In your php script, variable passed from jQuery will be available like this

$_POST['phpvar']
share|improve this answer
How this works: when you change select option, it will create a request to script.php – Alex Oct 2 '12 at 8:36
P.S I forgot, you need function(data) in $.post, then in data variable you will see the responce – Alex Oct 2 '12 at 8:38
thnx for the answer but which is which? which one gous in the serverside code and which is the script code in the main page? – Lynyrd Salita Oct 2 '12 at 8:51
in jQuery AJAX variables are passed like this server_var: javascript_var. So in my sample I get value from selectbox, assign it to javascript variable value and pass it to server as value of phpvar. That means, in php you will get the passed value from $_POST['phpvar'] – Alex Oct 3 '12 at 13:02

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