futurefind.js

jQuery.fn.futureFind = function futureFind(query, callback) {

    function startLooking(el, query, initialElement, localEventID) {

        var observer;

        function stopLooking() {
            observer.disconnect();
        }

        observer = new MutationObserver(function (mutations) {
            var results = el.find(query);
            if (results.length > 0) {
              if(callback) callback(results);
              $(initialElement).trigger(localEventID, [results]);
              stopLooking();
            }
        });

        observer.observe(el[0],
        {
            childList: true,
            subtree: true,
            attributes: false,
            characterData: false
        });
    }

    var initialElement = $(this[0]);

    var localEventID = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
        var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16);
    });

    // If we are not the first in the chain
    if (this.eventID) {
        // When the one in the chain above us completes start looking.
        $(initialElement)
            .on(this.eventID,
                function (e, results) {
                    startLooking(results, query, initialElement, localEventID);
                    this.eventID = localEventID;
                });
    } else {
        // Start looking imedietly because we are the first in the chain.
        startLooking(initialElement, query, initialElement, localEventID);
    }

    // Pass the ID for when this find completes on to the next one in the chain.
    this.eventID = localEventID;

    return this;
};