Passing javascript variable to PHP function

Question

I have this javascript code

<Script>
 function getGroupId(){
 var group=document.getElementById("selectedOptions").value;
 var groupFirstLetter=group.substring(2);
 }
</Script>

I need to pass the groupFirstLetter to a PHP function which will count how many users in this group and return the value to the javascript function.

Any ideas please?

Thanks,

• Mohammer: there are only 2 ways to archieve that. 1. Ajax 2. reload page. JS runs in your client, PHP on the server. as soon as you requested a page and got your answer there is nothing happening on the server anymore (except for sockets or ajax). Without those 2 options you cant let js communicate with php

Answer 1

You can use jQuery for that to post an AJAX request. See this example taken out of jQuery documentation:

$.ajax({
 type: "POST",
 url: "some.php",
 data: {groupFirstLetter:groupFirstLetter},
 complete: function(data){
 //data contains the response from the php file.
 //u can pass it here to the javascript function
 }
});

The variable will be available in your PHP code as $_POST['groupFirstLetter']. You can manipulate it as you wish then echo a response to the browser again and it will be available in the data variable. references:

jQuery AJAX

Answer 2

As javascript runs on user's browser you have to do an http request to a php page. POST or GET can be used to send parameters.

To make a http call with javascript refer to this: HTTP GET request in JavaScript?

Answer 3

Use jQuery (jquery.com).

Dynamically load the php-file sending the variable using ajax like so:

$.post("file.php", {variable_name: value}, function(returned_data){
 console.log(returned_data); //or do whatever you like with the variable
});

and your php-file will access the variable as:

$_POST['variable_name'];