JavaScript preprocessors can help make authoring JavaScript easier and more convenient. For instance, CoffeeScript can help prevent easy-to-make mistakes and offer a cleaner syntax and Babel can bring ECMAScript 6 features to browsers that only support ECMAScript 5.

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.

+ add another resource

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.

` ````
<canvas id='canv'></canvas>
```

` ````
body {
overflow: hidden;
margin: 0;
padding: 0;
background: hsla(242, 30%, 5%, 1);
}
canvas {
width: 100%;
}
```

` ````
/*
(Book REF) HTML5 Canvas Ch. 5: Math, Physics, and Animation ::: Uniform Circular Motion
By Steve Fulton and Jeff Fulton
*/
window.requestAnimFrame = (function() {
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();
window.addEventListener('load', start, false);
var c,
$,
w,
h,
msX,
msY,
midX,
midY,
num = 650,
parts = [],
begin = 50,
repeat = 20,
end = Math.PI * 2,
force = null,
msdn = false;
function start() {
c = document.getElementById('canv');
$ = c.getContext('2d');
w = c.width = window.innerWidth;
h = c.height = window.innerHeight;
midX = w / 2;
midY = h / 2;
force = Math.max(w, h) * 0.09;
flow = begin;
window.requestAnimFrame(create);
run();
}
function run() {
window.requestAnimFrame(run);
go();
}
function Part() {
this.deg = 0;
this.rad = 0;
this.x = 0;
this.y = 0;
this.distX = 0;
this.distY = 0;
this.color = 'rgb(' + Math.floor(Math.random() * 130) + ',' + Math.floor(Math.random() * 50) + ',' + Math.floor(Math.random() * 100) + ')';
this.size;
}
function create() {
var n = num;
while (n--) {
var p = new Part();
p.deg = Math.floor(Math.random() * 360);
p.rad = Math.floor(Math.random() * w * 0.5);
p.x = p.distX = Math.floor(Math.random() * w);
p.y = p.distY = Math.floor(Math.random() * h);
p.size = 1 + Math.floor(Math.random() * (p.rad * 0.055));
parts[n] = p;
}
c.onmousemove = msmv;
c.onmousedown = msdn;
c.onmouseup = msup;
var int = setInterval(function() {
flow--;
if (flow === repeat) clearInterval(int);
}, 20);
}
function go() {
$.globalCompositeOperation = 'source-over';
$.fillStyle = 'hsla(242, 30%, 5%, .55)';
$.fillRect(0, 0, w, h);
$.globalCompositeOperation = 'lighter';
var mx = msX;
var my = msY;
var bounds = force;
if (msdn) {
bounds = force * 2;
}
var n = num;
while (n--) {
var p = parts[n];
var radi = Math.PI / 180 * p.deg;
p.distX = midX + p.rad * Math.cos(radi);
p.distY = midY + p.rad * Math.sin(radi) * 0.4;
if (mx && my) {
var react = Math.floor((bounds * 0.5) + Math.random() * (bounds * 0.9));
if (p.distX - mx > 0 &&
p.distX - mx < bounds &&
p.distY - my > 0 &&
p.distY - my < bounds) {
p.distX += react;
p.distY += react;
} else if (p.distX - mx > 0 &&
p.distX - mx < bounds &&
p.distY - my < 0 &&
p.distY - my > -bounds) {
p.distX += react;
p.distY -= react;
} else if (p.distX - mx < 0 &&
p.distX - mx > -bounds &&
p.distY - my > 0 &&
p.distY - my < bounds) {
p.distX -= react;
p.distY += react;
} else if (p.distX - mx < 0 &&
p.distX - mx > -bounds &&
p.distY - my < 0 &&
p.distY - my > -bounds) {
p.distY -= react;
p.distY -= react;
}
}
p.x += ((p.distX - p.x) / flow);
p.y += ((p.distY - p.y) / flow);
var x = p.x;
var y = p.y;
var s = p.size * (p.y * 1.5 / h);
if (s < 0.1) {
s = 0;
}
$.beginPath();
$.fillStyle = p.color;
$.arc(x, y, s, 0, end, true);
$.fill();
$.closePath();
var vary;
if (p.size < 2) {
vary = 4;
} else if (p.size < 3) {
vary = 3;
} else if (p.size < 4) {
vary = 2;
} else {
vary = 1;
}
vary *= (p.y / (h * 0.9));
p.deg += vary;
p.deg = p.deg % 360;
}
}
function msmv(e) {
var p = getPos(e.target);
var sX = window.pageXOffset;
var sY = window.pageYOffset;
msX = e.clientX - p.x + sX;
msY = e.clientY - p.y + sY;
}
function msdn(e) {
msdn = true;
}
function msup(e) {
msdn = false;
}
function getPos(el) {
var cosmo = {};
cosmo.x = el.offsetLeft;
cosmo.y = el.offsetTop;
while (el.offsetParent) {
el = el.offsetParent;
cosmo.x += el.offsetLeft;
cosmo.y += el.offsetTop;
}
return cosmo;
}
```

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