Change PHP variable via AJAX - php

Question

Hi I need set value of PHP variable to "1" if clients screen resolution is more then 1200px (I check only width) and set value of this variable to "2" if client have screen smaller then 1200px.
To check clients width of screen I use JQuery function "$( window ).outerWidth(true)". If PHP can check clients resolution then I don´t need wrote this question, but PHP not allow this and for that I search for solution of this problem.
=> How can I write script which allow change PHP variable before client load page? I mean I need AJAX, but I don´t know how used it.
Sorry for this maybe simply question. Can someone help me?

Answer 1

This might help ,
var width = $(window).width();
var height = $(window).height();
var screenTimer = null;
function Screen (){
$(window).resize(function() {
height = $(window).height();
width = $(window).width();
getScreen ();
});
function getScreen (){
return { 'height' : getHeight (), 'width': getWidth () };
}
screenTimer = setInterval ( getScreen (), 50 );
}
function getHeight (){
console.log ( 'height: ' + height);
$('#height').text(height);
return height;
}
function getWidth (){
console.log ( 'width: ' + width);
$('#width').text(width);
return width;
}
Screen ();
put this code in php along with script tag and set your variable.

Answer 2

Impossible I get it... Finally a write this:
index.php:
<script type="text/javascript">
$(document).ready(function() {
var sirka_monitoru = $( window ).outerWidth();
if ( sirka_monitoru < 1200 ){
$.post("soubor1.php", { nejaka: "1111" }, function (msg)
{
$('.some_name').html(msg);
});
}
else{
$.post("soubor2.php", { nejaka: "2222" }, function (msg)
{
$('.some_name').html(msg);
});
}
}); //END $(document).ready()
</script>
<div class="some_name"></div>
soubor1.php (1st file to include) file soubor2.php is similar to soubr1.php
<?php
echo "Value: " . $_POST["nejaka"];
?>
<div style="width: 100%; float: left; background-color: green; height: 100px;">
soubor1
</div>
=> When I load page then check width of users screen and after that I can load different PHP files and send him some important variables to solved my problem from question.
=> I accept my answer and solved this queston and close it