How to call a php script/function on a html button click

Question

Before someone has a go at me or marks this down, I have looked all over the internet to find out how to do this (including the same question on stackoverflow). I'm new, and I am finding it very hard to learn new concepts so please be easy on me.

What I want to do is call a php script/function on a button click. I have this running in WAMP if that helps. Here's my code:

<?php include 'the_script.php'; ?>

<button type="button" onclick="the_function()">Click Me</button>

the_script.php has this in it:

the_function() {
    echo "You win";
}

Why isn't this working? I've heard about the button being client side etc. and PHP being server-side, which means that you cannot link the two together. I know that you have to use AJAX to make this work, however I legitimately have absolutely no clue how to do it. I've tried googling it etc., however I can't find anything. I know how to use AJAX and call events with it, however I still have no idea how to make it call a PHP script.

Can you please make your answers as clear and simple as possible, I'm new to this

Thanks for the help :)

EDIT ***

For some reason wherever I go everyone's code is different. The way I have been taught AJAX looks completely different. Can you please write it this way so I can understand? Thanks, here's an example:

var request;

if (window.XMLHttpRequest) {
    request = new XMLHttpRequest();
} else {
    request = new ActiveXObject("Microsoft.XMLHTTP");
}

request.open('GET', 'file.php', true);

request.onreadystatechange = function() {

    if (request.readyState===4 && request.status===200) {
        do stuff
    }
}

request.send();

Answer 1

Just try this:

<button type="button">Click Me</button>
<p></p>
<script type="text/javascript">
    $(document).ready(function(){
        $("button").click(function(){

            $.ajax({
                type: 'POST',
                url: 'script.php',
                success: function(data) {
                    alert(data);
                    $("p").text(data);

                }
            });
   });
});
</script>

In script.php

<?php 
  echo "You win";
 ?>

Answer 2

Of course AJAX is the solution,

To perform an AJAX request (for easiness we can use jQuery library).

Step1.

Include jQuery library in your web page

a. you can download jQuery library from jquery.com and keep it locally.

b. or simply paste the following code,

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>

Step 2.

Call a javascript function on button click

<button type="button" onclick="foo()">Click Me</button>

Step 3.

and finally the function

 function foo () {
      $.ajax({
        url:"test.php", //the page containing php script
        type: "POST", //request type
        success:function(result){
         alert(result);
       }
     });
 }

it will make an AJAX request to test.php when ever you clicks the button and alert the response.

For example your code in test.php is,

<?php echo 'hello'; ?>

then it will alert "hello" when ever you clicks the button.