Using requestAnimationFrame() for performance checking

raf-performance-checking.js

/**
 * Performance Checking
 *
 * Will enable and disable a flag on the window object
 * When Javascript performance suffers, so that optional features
 * Can be Disabled or delayed
 */
(function () {
	var lastTimestamp = + new Date();

    /**
     * Compares the execution of requestAnimationFrame to it's ideal, 60fps.
     * When Javascript is performant, the difference should approach 16ms.
     * When experiencing degraded Javascript performance, this value will begin to increase.
     * If it reaches 32, we toggle the flag `window.performant`, which other
     * functions can use to turn off the execution of optional features
     */
	function perfCheck () {
	  var difference = + new Date() - lastTimestamp;
	  lastTimestamp = + new Date();

	  if (difference > 32) {
	  	window.performant = false;
	  } else {
	  	window.performant = true;
	  }
	  
	  requestAnimationFrame(perfCheck);
	}
	requestAnimationFrame(perfCheck);
})();

/**
 * Deferred Execution
 */
var deferredExecutionTimers = window.deferredExecutionTimers = {};

function s4 () {
  return Math.floor((1 + Math.random()) * 0x10000).toString(16).substring(1);
}

function deferExecution (condition, callback, interval) {
  
  if (!deferredExecutionTimers) window.deferredExecutionTimers = {};
  
  // Generate a new UUID to track this timer
  var uuid = s4() + s4() + s4();
  interval = interval || 1000;
  
  deferredExecutionTimers[uuid] = setInterval(function () {
    if (condition && typeof(condition) === "function") condition = condition();
  
    if (condition) {
      if (callback && typeof(callback) === "function") callback();
      clearTimeout(deferredExecutionTimers[uuid]);
    }
  }, interval);
}