Lazy Load The Facebook Comments Plugin Using JavaScript

functions.php

<script>
function loadAPI() {
    var js = document.createElement('script');
    js.src = '//connect.facebook.net/en_US/sdk.js#xfbml=1&appId=YOUR_APP_ID&version=v2.0';
    document.body.appendChild(js);
}

window.onscroll = function () {
    var rect = document.getElementById('comments').getBoundingClientRect();
    if (rect.top < window.innerHeight) {
        loadAPI();
        window.onscroll = null;
    } 
}
</script>

<div id="fb-root"></div>

<div id="comments" class="fb-comments" data-href="YOUR_WEBPAGE" data-numposts="5" data-colorscheme="light"></div>