what url should i use on AJAX to execute a specific file?

I need a button that calls a php code, the button is written in the single.php file, so I’m trying it with AJAX post function, but i don’t know what URL should i put to call theme files, since the Theme API is php, not javascript.

I was trying to use window.location.href, dumb move, yeah, the single.php file isn’t loaded directly.

Here is my current code

HTML:

<button type="button" onclick="return likeTrigger();" class="btn btn-info btn-lg pulse" style="color: #000;">
	<div id="likesCount" style="display: inline;"><?php echo getLikes(get_the_ID()); ?></div>
	<span class="glyphicon glyphicon-thumbs-up" aria-hidden="true"></span>
</button>
<button type="button" onclick="return unlikeTrigger();" class="btn btn-danger btn-lg pulse" style="color: #000;">
	<div id="unlikesCount" style="display: inline;"><?php echo getUnlikes(get_the_ID()); ?></div>
	<span class="glyphicon glyphicon-thumbs-down" aria-hidden="true"></span>
</button>

JS:

function likeTrigger(){
    $.post(
        window.location.href,
		{event: "like", csIP: getIP()},
        function (response) {
            $('#likesCount').html(response.responseText);
        }
	);
    return false;
}
function unlikeTrigger(){
    $.post(
        window.location.href,
		{event: "unlike", csIP: getIP()},
        function (response) {
            $('#unlikesCount').html(response.responseText);
        }
	);
    return false;
}

php(just a test, not the actual code)

if($_POST["event"] == "like" or $_POST["event"] == "unlike")
{
	echo "hello";
}

I already tested the following stuff

1. Button is triggering
2. Like and unlike trigger functions are being called
3. PHP file isn’t being accessed

Thanks in advance.