Rotating logos - fade-in/fade-out [one-at-a-time] (no carousel)

jquery.rotate-logos.js

// Client logos

var logoEls = $('.social-proofs .clientLogo'),
    logoCount = logoEls.size(),
    unusedLogos = [{
        src: 'img/companies-we-represent/house-of-raeford.png',
        alt: 'YOUR COMPANY serves House of Raeford'
    }, {
        src: 'img/companies-we-represent/pictsweet.png',
        alt: 'YOUR COMPANY serves Pict-Sweet'
    }],
    lastIdx,
    penultimateIdx;
setInterval(function() {
    var idx;
    do {
        idx = Math.floor(Math.random() * logoCount);
    } while (idx == lastIdx || idx == penultimateIdx);
    penultimateIdx = lastIdx;
    lastIdx = idx;
    var selected = logoEls.eq(idx);
    selected.fadeTo(500, 0, function() {
        unusedLogos.unshift({
            src: selected.attr('src'),
            alt: selected.attr('alt')
        });
        selected.attr(unusedLogos.pop());
        selected.fadeTo(1100, 1);
    });
}, 3000);

logos.html

<!-- trusted-brands-we-serve Section -->
<section id="trusted">
    <div class="container">
        <div class="row">
            <div class="col-lg-12 text-center">
                <h2 class="section-heading">Companies we represent</h2>
            </div>
        </div>

        <!-- logos -->
        <div class="row row-eq-height social-proofs">
            <div class="col-sm-3 img-centered">
                <div class="text-center">
                    <img src="img/companies-we-represent/pilgrims.png" class="img-responsive img-centered clientLogo">
                    <!-- Pilgrims -->
                </div>
            </div>
            <div class="col-sm-3">
                <div class="text-center">
                    <img src="img/companies-we-represent/seaboard-farms.png" class="img-responsive img-centered clientLogo">
                    <!-- Seaboard Pork -->
                </div>
            </div>
            <div class="col-sm-3">
                <div class="text-center">
                    <img src="img/companies-we-represent/prariefresh.png" class="img-responsive img-centered clientLogo">
                    <!-- Prarie Fresh -->
                </div>
            </div>
            <div class="col-sm-3">
                <div class="text-center">
                    <img src="img/companies-we-represent/peco.jpg" class="img-responsive img-centered clientLogo">
                    <!-- Peco -->
                </div>
            </div>
        </div>
    </div>
</section>