storing javascript variable in database in php

In php I am trying to get screen resolution of website visitor by 2 different javascript commands.

$width = "<script>var windowWidth = screen.width; document.writeln(windowWidth); </script>";
$height = "<script>var windowHeight = screen.height; document.writeln(windowHeight); </script>";

AND

$width = "<script>document.write(screen.width);</script>";
$height = "<script>document.write(screen.height);</script>";

$screenres = $width." x ".$height;

When I echo $screenres variable in php...

storing javascript variable in database in php

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