FadeIn a value from a hidden input once it is set.

FadeIn a value from a hidden input once it is set.

One of the things this code does is to set the value of a hidden input, #selectionveg1, and sets the text to be displayed via <span id="spanselectionXXX>. I would like to fade in and out the text when it changes. I tried using .fadeIn and .change, but I don't think the span element is right for this. Any suggestions?

$("body").on('click', '.yes31', function() {
        var parent = $(this).parent();
        var gpar = parent.parent()
        gpar.addClass('opt31selected');
        var thing = gpar.attr('id');
        $("body").find('#' + thing).addClass('opt31selected');
        $('#selectionveg1').val('onions');
        var foo = $('input#selectionveg1').val();
        $('#spanselectionveg1').text(foo);
    });
    $("body").on('click', '.no31', function() {
        $('.opt31selected').removeClass('opt31selected')
        $('#selectionveg1').val('');
        $('#spanselectionveg1').text('');
    });