1// Sometimes we need to substract values from a form.
2// Those come in as strings. So we need to convert them first.
3// We can do this with Number().
4var c = Number($_POST['a']) - Number($_POST['b']);
5// or
6var c = Number($_GET['a']) - Number($_GET['b']);
7// or FLOAT
8var c = Number.parseFloat($_POST['a']) - Number.parseFloat($_POST['b']);
9// or
10var c = Number.parseFloat($_GET['a']) - Number.parseFloat($_GET['b']);
11// or INTEGER
12var c = Number.parseInteger($_POST['a']) - Number.parseInteger($_POST['b']);
13// or
14var c = Number.parseInteger($_GET['a']) - Number.parseInteger($_GET['b']);