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Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

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Use npm Packages

We can make npm packages available for you to use in your JavaScript. We use webpack to prepare them and make them available to import. We'll also process your JavaScript with Babel.

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HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

              var counter = 1;

function printMessage() {
  console.log(`message ${counter++}`);

var schedule = Scheduler(/* debounceMinimum = */50,/* throttleMaximum = */500);

// try to schedule a message to be printed (after approx 50ms of debounce)

setTimeout(function waitAWhile(){
    // try to schedule next message to be printed (after approx 50ms of debounce)

  // but now keep flooding the scheduling, so it keeps debouncing, up to the 500ms max throttling
  var intv = setInterval(function(){ schedule(printMessage); },30);
  // stop the madness, after about 10 seconds!
  setTimeout(function(){ clearInterval(intv); },10*1000);

// "message 1" (printed after about 50ms)

// (waiting about 3.5 seconds)

// "message 2"
// "message 3"  (after another 500ms)
// "message 4"  (after another 500ms)
// ..

// ***********************

function Scheduler(debounceMin,throttleMax) {
	var entries = new WeakMap();

	return schedule;

	// ***********************

	function schedule(fn) {
		var entry;

		if (entries.has(fn)) {
			entry = entries.get(fn);
		else {
			entry = {
				last: 0,
				timer: null,

		var now =;

		if (!entry.timer) {
			entry.last = now;

		if (
			// no timer running yet?
			entry.timer == null ||
			// room left to debounce while still under the throttle-max?
			(now - entry.last) < throttleMax
		) {
			if (entry.timer) {

			let time = Math.min(debounceMin,Math.max(0,(entry.last + throttleMax) - now));
			entry.timer = setTimeout(run,time,fn,entry);

	function run(fn,entry) {
		entry.timer = null;
		entry.last =;
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