window.addEventListener('load', function() {

    var challenges = document.getElementById('challenges'),
        challenge, i, len;

    function change(e) {
        if(e && e.target && e.target.tagName === 'LI') {

            // if this func is called from the listener, check if it's the element we want
            e = e.target.querySelector('a.btn[data-action="play"][data-challenge-id]:not(atchd)');
            if(e) {
                e.setAttribute('atchd', '1'); // this is so we know we grabbed it already
                e.textContent = 'Accept [atchd]';
                processElem(e); // do a callback
            }
        } else {

            // if this func isn't called from the listener, grab all current un-grabbed buttons
            e = challenges.querySelectorAll('a.btn[data-action="play"][data-challenge-id]:not(atchd)');
            if(e.length !== 0) {
                len = e.length;
                for (i = 0; i < len; i += 1) {
                    challenge = e[i];
                    challenge.setAttribute('atchd', '1'); // this is so we know we grabbed it already
                    challenge.textContent = 'Accept [atchd]';
                    processElem(e); // do a callback
                }
            }
        }
    }

    function processElem(element) {
        // do whatever we want with the anchor node element
    }

    // it found the common ancestor
    if(challenges) {
        change(); // run it for the first time
        challenges.addEventListener('DOMNodeInserted', change, false); // listen for changes
    }

}, false);