Throw error if a group of inputs is over a certain sum

checkInputSum

function checkSum(groupOfInputs, maxValue) {
    groupOfInputs = $(groupOfInputs);
    groupOfInputs.on('change keyup paste', function() {
        $this = $(this);
        var values = groupOfInputs.map(function() {return $(this).val();}).get();
        var sum = values.reduce(function(one, two) {
            return Number(one) + Number(two);
        });
        if (sum > maxValue) {
            alert('Too big!');
            $this.val('').focus();
        }
    });
}
var checkSumThous = function(groupOfInputs) {
    return checkSum(groupOfInputs, 1000);
};
checkSum('.one', 1000);
checkSum('.two', 500);
checkSumThous('.three');