decay.js

this.decay = function(feat, time, callback) {
    var steps = 100;
    var ts = time / steps;
    for (var i = 0; i < steps; ++i) {
        var opacity = 1 - ((i / steps)*.5);
        (function(i, opacity){setTimeout(function() {
            feat.style.fillOpacity = opacity;
            feat.style.pointRadius = 4 * opacity;
            commentsLayer.drawFeature(feat);
            if (i == steps - 1) {
                callback(feat);
            }
        }, i * ts)})(i, opacity);
    }
};