#StackBounty: Lazy load content of slides inside carousel (content is oEmbeds/iframes)

Bounty: 100

I am loading in ajax a modal/popin with a Bootstrap carousel in which each slide is (not an image as in many question about lazy loading) but an iframe from oEmbed from various social networks (facebook, instagram, twitter, …).

The issue is that when I click the button that laods the modal, ALL the slides content get loaded, that is to say 15 to 20 oembeds(eahc of them loading content tetx, image and and javascript…).

I would like to be clever about it and only “lazy loading” slide by slide or even smarter 3 slides by 3 slides.

I am just also mentioning for the sake of information that I am using scrollMonitor and Hubspot Messenger. But i’d rather use Bootstrap slide events to trigger the apparition/load of each slide or any suggestion you would have.

I’m using ruby on rails as back end language

The url of the oEmbed programmatically change as they are inputed from a Admin Backoffice and change on each Article/page but you’ll find below an example :


//button to click to make modal appear
<a class="btn btn-primary" onclick="loadModal()" id="socialStoryModal">
      load modal

Load Modal with Hubspot Messenger in page.js

function loadModal() {  
      var msg;
      msg = Messenger().post({
        message:  'modal.html.erb',/see below the carousel
        showCloseButton: true,
        hideAfter: false

= Modal with the carousel and the social embeds (here can be up to 50 of them)

I’ve seen tons of libraries to lazy load images and even sometimes scripts/iframes but they all need to have directly add certain classes I n the block, which is of no help for me as I use oembed above and I have nowhere to put these lazy classes.

I need to make it work with these oEmbeds iframes.

Get this bounty!!!