jQuery snippet to monitor an element for an element to appear in the DOM, then duplicate its contents into another element.

monitor-then-duplicate.js

var cachedContentHtml = '';

window.setInterval(function() {
    var watchElem = $('.watch-me');

    // Check if "element" exists in DOM yet
    if ( watchElem.length ) { 
        // Grab the content we need
        var contentHtml = $('.content').html();

        // If content has changed, then update another element
        if ( cachedContentHtml != contentHtml ) { 
            // Save a new cached html value
            cachedContentHtml = contentHtml;
            
            // Update the duplicate element
            $('.duplicate-elem').html( contentHtml );
        }
    }
}, 1000);