how do i slove this problem

[frank1]

i dont know much about js

any way i am uisng ajax to dynamically generate second drop down based on value selected on first drop down
ie
form file
<script src="getsome.js"></script>
<select name="fieldname " onChange="showUser(this.value)">

and in js file i have this

f (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="get.php"
url=url+"?q="+str
url=url+"&sid="+Math.random()


so the problem with that is every file i use this ajax (with some modification) i have to 2 news files... .js and .php to get second drop down

so there has been many files....
so is there any way to solve this problem and make use of only two files in all cases...
i am thinking of passing some varibale from form php to .js file and make some condition ..to chose the get.php file....
ie
if somevalue
var url="get.php"
else if somevalue
var url="get1.php"
and so on

but even that way i need to have separate get page in all

any way to eliminate need to two new file every thing i use this ajax in new file...
thanks

[crmalibu]

ajax-reply.php?command=getTime&args=foo
ajax-reply.php?command=makeBagels&args=bar
etc...

[frank1]

ajax-reply.php?command=getTime&args=foo
ajax-reply.php?command=makeBagels&args=bar
etc...

i think my question is not understood any way sorry for that
here scenario is

form.php
which should send variable to js file

ok may be we can do test.js?var1=value

but i dont know how can js file handle variable sent from php file

then in js file based on the variable taken from form.php (first php file)
we should call another file(variable passing is easy here from js to php...url=url+"?q="+str)
the problem here is passing variable value from php to .js file and make decision in js file based on that variable value (may be using if...)

thanks

[frank1]

ok my my intermediate solution

i have included js file script with in .php file now
so when i have two files which should use ajax drop down...(ok for eg first one shows second drop down of subcategories based on value of first dropdown...)
and second get username taking username start variable from one drop down

if my old case i had
for 1st case
form1.php
getcategories.js(called by form1.php)
getcategories.php (called by js file)

and again
form2.php
getusers.js(called by form1.php)
getusers.php (called by js file)

but now i have
form1.php
getajax.php (now it has both js and php)
more over now
in getajax.php i use variable name $block
if ($block==1)
{
getcategories
}
else if ($block==2)
{
getusers;
}

and in form1 i include
<?php
$block=1;
include('getajax.php');
....

in form 2 i do
$block=2;
include('getajax.php');
....

and i onclick of both form's select (first select which gives value to second drop down...)
onChange="showvalues(this.value)"...
which is defined in <script> part of getajax.php

any way it has been working fine so far...
if any suggestion or ...i may get problem in future...please suggest...

any way as it has been complicated....if not understood sorry for that..

any way thanks

any improvements...?

[gRoberts]

I'd use crmalibu's suggestion:

switch($_GET['command']) {
    case 'block1' :
        getcategories();
    break;
    case 'block2' :
        getusers();
    break;
    // etc...
}

I'd also use post variables instead of get. This way you can pass more data and handle it easier (just incase your passed variables contain something that can't be sent via GET)