Filter table from <select> input using jQuery

Answer 1

Try this. If necessary substitute y with $(y).

$('tr').hide();
$('select').change( function(){
    var letter = $(this).val();
    var dataset = $('#tableID').find('td');
    $.each(dataset, function(x, y){
        if( y.substr(0,1) == letter){
            y.parent().show();
        }
    });
});

Edit

@SolutionYogi. You are right. I guess this line can be rewriten as:

var dataset = $('#tableID').find('tr').children('td').slice(0,1);

Never tried that though.

EDIT 2

I tested this. I hope is elegant enough as well and I doesn't have more errors.

$('tr').hide();
$('select').change( function(){
    var letter = $(this).val();
    var dataset = $('#tableID').find('tr');
        $.each(dataset, function(x, y){
            var data = $(y).children().slice(0,2);
                $.each(data, function(a, b){
                    if( $(b).html().substr(0,2) == letter){
                        $(b).parent().show();
                    }
             });
       });
});