var converter = function() {
                var = from = document.units.elements.from,
                fromWhat = document.units.elements.fromWhat,
                to = document.units.elements.to,
                toWhat = document.units.elements.toWhat;

                if (fromWhat.value === "Convert from" && toWhat.value === "Convert to") {
                        alert("Please choose what you want to convert, and what you want it be converted to.");
                        } else if (fromWhat.value === "Convert from") {
                                alert("Please choose what you want to convert.");
                        } else if (toWhat.value === "Convert to") {
                                alert("Please choose what you want to convert to.");
                        } else if ((isNaN(from.value) === true) || (isNaN(to.value) === true) || (from === null) || (from.value === undefined)) {
                                alert("Please enter a number.");
                        }

    else {
                        to.value = fromWhat.value*fromWhat.value/toWhat.value;

    }
    return false;
};