Floating kittens bookmarklet.

KittensBookmarklet.js

javascript:(function(){if ((typeof spawnKitten) === "function") {spawnKitten();} else {var element = document.createElement("script");element.type = "text/javascript";element.src = "https://gist.github.com/Equinox-/7783216/raw/TheScript.js";document.head.appendChild(element);}})();

TheScript.js

function updateKittens() {
	if ((typeof window.maxSpeed) != 'number') {
		window.maxSpeed = 7;
	}
	if ((typeof window.gravConstant) != 'number') {
		window.gravConstant = .4;
	}

	var children = document.getElementById("kitten_container").children;
	for (var j = 0; j<children.length; j++){
		var element = children[j];
		if (element.id.indexOf("kitten") == 0){
		    var x = parseFloat(element.posX) + parseFloat(element.velX);
		    var y = parseFloat(element.posY) + parseFloat(element.velY);
			var massA = parseFloat(element.width) * parseFloat(element.height);
			for (var l = 0; l<children.length; l++){
				var other = children[l];
				if (l != j && other.id.indexOf("kitten") == 0){
				    var x2 = parseFloat(other.posX);
				    var y2 = parseFloat(other.posY);
				    var len = Math.sqrt((x2-x) * (x2-x) + (y2-y) * (y2-y));
				    var normalX = (x2 - x) / len;
				    var normalY = (y2 - y) / len;
					var massB = parseFloat(other.width) * parseFloat(other.height);
				  //  element.velX += gravConstant * Math.sqrt(massA * massB) * normalX / len / len;
				   // element.velY += gravConstant * Math.sqrt(massA * massB) * normalY / len / len;
				    var collideOnBoth = false;// workaround for a bigger, more complicated issue
				    if (y < y2 + other.height && y + element.height > y2 && (!collideOnBoth || Math.abs(element.velY) > Math.abs(element.velX))) {
					    if (x + element.width > x2 && x < x2) {
					    	element.velX = -Math.abs(parseFloat(element.velX));
					    	//x = x2 - element.width;
					    }
					    if (x < x2 + other.width && x + element.width > x2 + other.width) {
							element.velX = Math.abs(parseFloat(element.velX));
							//x = x2 + other.width;
					    }
					}
				    if (x < x2 + other.width && x + element.width > x2 && (!collideOnBoth || Math.abs(element.velX) > Math.abs(element.velY))) {
					    if (y + element.height > y2 && y < y2) {
					    	element.velY = -Math.abs(parseFloat(element.velY));
					    	//y = y2 - element.height;
					    }
					    if (y < y2 + other.height && y + element.height > y2 + other.height) {
							element.velY = Math.abs(parseFloat(element.velY));
							//y = y2 + other.height;
					    }
					}
				}
			}
			if (element.velX > maxSpeed) {
				element.velX = maxSpeed;
			} else if (element.velX < -maxSpeed) {
				element.velX = -maxSpeed;
			}
			if (element.velY > maxSpeed) {
				element.velY = maxSpeed;
			} else if (element.velY < -maxSpeed) {
				element.velY = -maxSpeed;
			}


		    if (x + element.width > document.body.scrollWidth) {
		    	element.velX = -Math.abs(parseFloat(element.velX));
		    	x = document.body.scrollWidth - element.width;
		    } else if (x < 0) {
				element.velX = Math.abs(parseFloat(element.velX));
			x = 0;
		    }
		    if (y + element.height > document.body.scrollHeight) {
		    	element.velY = -Math.abs(parseFloat(element.velY));
		    	y = document.body.scrollHeight - element.height;
		    } else if (y < 0) {
		    	element.velY = Math.abs(parseFloat(element.velY));
		    	y = 0;
		    }

		    element.posX = x;
		    element.posY = y;
		    element.style.left = Math.round(x) + "px";
		    element.style.top = Math.round(y) + "px";
		}
	}
}

function spawnKitten() {
	var element = document.createElement("img");
	var width = (50 + parseInt(Math.random() * 250));
	var height = (50 + parseInt(Math.random() * 250));
	element.src = "http://placekitten.com/" + width + "/" + height;
	element.id = "kitten";
	element.style.position = "absolute";
	var x = parseFloat(Math.random() * (document.body.scrollWidth - width));
	var y = parseFloat(Math.random() * (document.body.scrollHeight - height));
	element.posX = x;
	element.posY = y;
	element.style.left = Math.round(x) + "px";
	element.style.top = Math.round(y) + "px";
	element.style.width = width + "px";
	element.style.height = height + "px";
	element.style.zIndex = 100000;
	element.style.pointerEvents = "auto";
	element.velX = (parseFloat(Math.random() * 2) - 1) * 10;
	element.velY = (parseFloat(Math.random() * 2) - 1) * 10;
	element.onclick = function() {
                var audio = window.kittenSound[Math.floor(window.kittenSound.length * Math.random())];
                audio.volume = 1;
                audio.play();
		this.remove();
	};
	document.getElementById("kitten_container").appendChild(element);
	window.kittenSound = [];
	for (var i = 1; i<9; i++) {
	      window.kittenSound.push(new Audio("http://www.kessels.com/catsounds/cat" + i + ".wav"));
	}
}

if (document.getElementById("kitten_container") == undefined) {
	var container = document.createElement("div");
	container.style.position = "absolute";
	container.style.left = "0px";
	container.style.top = "0px";
	container.style.width = "100%";
	container.style.height = "100%";
	container.id = "kitten_container";
	container.style.zIndex = 10000;
	container.style.pointerEvents = "none";
	container.style.overflow = "visible";
	document.body.appendChild(container);
	window.mouse = {"x":0, "y":0};
	setTimeout(function(){
	container.addEventListener("mousemove", function (e){window.mouse.x = e.x; window.mouse.y = e.y;}, false);
	}, 1000);
	console.log("Kitten maker: " + setInterval(updateKittens, 25));
}

spawnKitten();