Monitor JS garbage collection

gc.js

// run this in Chrome with the --enable-precise-memory-info flag
// $ open -a "Google Chrome" --args --enable-precise-memory-info

timer = function() {
	requestAnimationFrame(timer)

	var heapBefore = window.performance.memory.usedJSHeapSize

	// run processes here
	// eg. console.log allocates 2216 bytes, new Object() 56 bytes

	var heapAfter = window.performance.memory.usedJSHeapSize;
	// account for 40 bytes allocated to run this function
	var heapDiff = (heapAfter - heapBefore) - 40;
  
  	// heapDiff < 0 indicates a garbage collection occurred
	if (heapDiff < 0) {
		console.log("gc:", heapDiff);
	}
}

requestAnimationFrame(timer)

Test it out with this pen: http://codepen.io/lukehedger/pen/bNOogj

Resources:

• How much garbage is my JS producing
• Browser garbage collection and framerate