Multiple Select limit number of selection

Answer 1

You are using this inside change event, which is reference to select.

Try this:

$("select").on('click', 'option', function() {
    if ($("select option:selected").length > 3) {
        $(this).removeAttr("selected");
        // alert('You can select upto 3 options only');
    }
});

Demo: http://jsfiddle.net/tusharj/tmkzebnj/

EDIT

$("select").on('change', function(e) {
    if (Object.keys($(this).val()).length > 3) {
        $('option[value="' + $(this).val().toString().split(',')[3] + '"]').prop('selected', false);
    }
});

Demo: http://jsfiddle.net/tusharj/tmkzebnj/1/