Run only once every X seconds (timer)

date.js

/**
 * This version uses Date to detect cooldown
 * Much better performance than with Timer
 */

var cooldownTime = 2000, // ms
	nextRun = null;

function run() {
	// Your code here
	console.log( 'Run my stuff! ' + Date.now() );
}

function clicked() {

	var now = +new Date; // IE8 compatibility http://afuchs.tumblr.com/post/23550124774/date-now-in-ie8

	if (!nextRun || nextRun <= now) {
		nextRun = now + cooldownTime;
		run();
	}
}

document.addEventListener('click', clicked);

timer.js

/**
 * This version uses a Timer
 * It is recommended to use the Date version instead
 */

var COOLDOWN_TIME = 2000, // ms
	wait = false,
	t;

function runner() {
  // Your code here
	console.log( 'Run my stuff! ' + Math.random(100) );
}

function cooler() {
	if (wait === false) {

		runner();

		t = setTimeout(function(){
			wait = false;
		}, COOLDOWN_TIME);
	}
	wait = true;
}

document.addEventListener('click', cooler);