JS
(quick guide & example)
<form onsubmit="return add();"> X = <input type="number" id="varX"> Y = <input type="number" id="varY"> X+Y = <input type="number" id="varR"> <input type="submit" value="Add"> </form>
function add () { GET VALUES FROM TEXT BOXES var x = document.getElementById ("varX").value; var y = document.getElementById ("varY").value;
ADD NUMBERS - X & Y ARE STRINGS! PARSE TO INT BEFORE ADD var result = parseInt(x) + parseInt(y);
OUTPUT RESULT document.getElementById ("varR").value = result; return false; }