Insert ellipsis (...) into HTML tag if content too wide

The following CSS only solution for truncating text on a single line works with all browers listed at http://www.caniuse.com as of writing with the exception of Firefox 6.0. Note that JavaScript is totally unnecessary unless you need to support wrapping multiline text or earlier versions of Firefox.

.ellipsis {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    -o-text-overflow: ellipsis;
}

If you need support for earlier versions of Firefox check out my answer on this other question.

I've got a solution working in FF3, Safari and IE6+ with single and multiline text

.ellipsis {
    white-space: nowrap;
    overflow: hidden;
}

.ellipsis.multiline {
    white-space: normal;
}

<div class="ellipsis" style="width: 100px; border: 1px solid black;">Lorem ipsum dolor sit amet, consectetur adipisicing elit</div>
<div class="ellipsis multiline" style="width: 100px; height: 40px; border: 1px solid black; margin-bottom: 100px">Lorem ipsum dolor sit amet, consectetur adipisicing elit</div>

<script type="text/javascript" src="/js/jquery.ellipsis.js"></script>
<script type="text/javascript">
$(".ellipsis").ellipsis();
</script>

jquery.ellipsis.js

(function($) {
    $.fn.ellipsis = function()
    {
        return this.each(function()
        {
            var el = $(this);

            if(el.css("overflow") == "hidden")
            {
                var text = el.html();
                var multiline = el.hasClass('multiline');
                var t = $(this.cloneNode(true))
                    .hide()
                    .css('position', 'absolute')
                    .css('overflow', 'visible')
                    .width(multiline ? el.width() : 'auto')
                    .height(multiline ? 'auto' : el.height())
                    ;

                el.after(t);

                function height() { return t.height() > el.height(); };
                function width() { return t.width() > el.width(); };

                var func = multiline ? height : width;

                while (text.length > 0 && func())
                {
                    text = text.substr(0, text.length - 1);
                    t.html(text + "...");
                }

                el.html(t.html());
                t.remove();
            }
        });
    };
})(jQuery);