so I try to get the width of the device using jquery I made responsive website with 2 interface for laptop and mobiles but the problem is it doesn't work in mobile even the dimension of the div test was out of size in mobiles please help me the code that I use for redirecting is below with comments
<html>
<head>
<script src="./js/jquery-3.2.1.js"></script>
</head>
<body>
<div id='test' style=" width: 2.54cm; height:2.54cm;"></div>
//this div dimension works on laptop it measure exactly 2.54cm or 1nch
//using ruler but in mobiles it shrink and out of measure
<script>
//as you see I get the width of the div to get the pixel per inch
var sqw=$('#test').width();
var sqh=$('#test').height();
//and I get the total width of the document
var dheight=$(document).height();
var dwidth=$(document).width();
var w=dwidth/sqw;
//and I divide the total width of the document to pixel per inch
//the problem is the mobile show 10.98 inch where the mobile I use is
//miniFlare S5 cherrymobile with width of just 2.5 inches
if(w<=7) {
window.location.replace("./m_index.php");
} else {
window.location.replace("./d_index.php");
}
</script>
</body>
</html>