gistfile1.js

        $('textarea').bind('click', function(){
            var currentChar = $(this)[0].selectionEnd;
            var all = $(this)[0].textLength;
            var line = 0;

            for (i = 0; i <= all; i++) {
                var char = $(this).text()[i];

                if (char == "\n") {
                    line++;
                }
                if (i >= currentChar && char == "\n") {
                    alert(line);
                    break;
                }
            }
        });