dc.events = {
    current: null
};

/**
 * This function triggers a throttled event function with a specified delay (in milli-seconds).  Events
 * that are triggered repetitively due to user interaction such brush dragging might flood the library
 * and invoke more renders than can be executed in time. Using this function to wrap your event
 * function allows the library to smooth out the rendering by throttling events and only responding to
 * the most recent event.
 * @name events.trigger
 * @memberof dc
 * @example
 * chart.on('renderlet', function(chart) {
 *     // smooth the rendering through event throttling
 *     dc.events.trigger(function(){
 *         // focus some other chart to the range selected by user on this chart
 *         someOtherChart.focus(chart.filter());
 *     });
 * })
 * @param {Function} closure
 * @param {Number} [delay]
 */
dc.events.trigger = function (closure, delay) {
    if (!delay) {
        closure();
        return;
    }

    dc.events.current = closure;

    setTimeout(function () {
        if (closure === dc.events.current) {
            closure();
        }
    }, delay);
};