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.

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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=c></canvas>
<div id=overlay></div>
<p> followers on codepen: thank <span>you</span> so much! </p>
```

` ````
canvas {
position:absolute;
top: calc( 50vh - 200px );
left: calc( 50vw - 300px );
background-color: #111;
}
#overlay {
position:absolute;
top: calc( 50vh - 200px );
left: calc( 50vw - 300px );
width: 600px;
height: 400px;
background: radial-gradient( ellipse 300px 200px at 300px 200px, rgba( 0, 0, 0, 0 ), rgba( 0, 0, 0, .2 ), rgba( 0, 0, 0, .5 ) );
}
body {
background-color: #090909;
}
p {
font: 20px Verdana;
color: hsl( 230, 50%, 40% );
text-shadow: 0 0 2px hsl( 230, 50%, 40% );
position: absolute;
top: calc( 50vh + 160px );
left: 0;
margin: 0 0;
width: 100vw;
text-align: center;
}
span {
font-size: 24px;
color: hsl(230, 50%, 55%)
}
```

` ````
/*
* This is my 100 followers special!
* Thanks to everyone for showing
* interesting in what I do, I really
* apreciate it! Hope you enjoy the pen!
*
*/
var w = c.width = 600,
h = c.height = 400,
ctx = c.getContext( '2d' ),
particleCount = 300,
spawnProb = 1,
hueStart = 200,
hueEnd = 260,
minSize = 5,
maxSize = 15,
speedMultiplier = .1,
alphaChanger = .05,
one = {
x: 90, w: 55,
y: 90, h: 210
},
r1 = 50,
r2 = 90,
f0 = { // first zero
x: 252,
y: 200,
},
s0 = { // second zero
x: 410,
y: 200,
}
particles = [],
squareR1 = r1 * r1,
squareR2 = r2 * r2,
leftest = one.x,
rightest = s0.x + r2,
highest = Math.min( one.y, f0.y - r2, s0.y - r2 ),
lowest = Math.max( one.y + one.w, f0.y + r2, s0.y + r2 ) + maxSize,
isInText = function( x, y ) {
// check if point is in 1, which is a rectangle
if( !( x < one.x || x > one.x + one.w ||
y < one.y || y > one.y + one.h) )
return true;
// check if point is in the 0s
else {
var dX = x - f0.x, // distance in the X from First zero
dY = y - f0.y, // distance in the Y from First zero
squareDist = dX * dX + dY * dY;
if( squareDist > squareR1 && squareDist < squareR2 )
return true;
dX = x - s0.x; // second zero
dY = y - s0.y;
squareDist = dX * dX + dY * dY;
if( squareDist > squareR1 && squareDist < squareR2 )
return true;
}
return false;
};
function loop() {
window.requestAnimationFrame( loop );
ctx.globalCompositeOperation = 'source-over';
ctx.fillStyle = '#111';
ctx.fillRect( 0, 0, w, h );
ctx.globalCompositeOperation = 'lighter';
step( true );
}
function step( render ) {
if( particles.length < particleCount && Math.random() < spawnProb )
particles.push( new Particle );
particles.map( function( par ) { par.step( render ); } );
}
function Particle() {
this.reset();
}
Particle.prototype.reset = function() {
this.bigness = 0;
this.hue = rand( hueStart, hueEnd ) |0;
this.size = rand( minSize, maxSize ) |0;
this.x = rand( leftest, rightest ) |0;
this.y = highest - this.size;
this.gradient = ctx.createRadialGradient( 0, 0, 0, 0, 0, this.size * 2);
this.gradient.addColorStop( 0, 'hsla(hue, 80%, 50%, .8)'.replace( 'hue', this.hue ) );
this.gradient.addColorStop( .5, 'hsla(hue, 80%, 50%, .8)'.replace( 'hue', this.hue ) );
this.gradient.addColorStop( 1, 'hsla(hue, 80%, 50%, .0)'.replace( 'hue', this.hue ) );
}
Particle.prototype.step = function( render ) {
this.y += speedMultiplier * this.size;
if( this.y - this.size > lowest ) this.reset();
if( isInText( this.x, this.y ) ){
if( this.bigness < 1 ) this.bigness += alphaChanger;
} else if( this.bigness > 0 ) this.bigness -= alphaChanger;
if( render && this.bigness > 0 ) {
ctx.fillStyle = this.gradient;
ctx.translate( this.x, this.y );
ctx.scale( this.bigness, this.bigness );
ctx.beginPath();
ctx.arc(0, 0, this.size * 2, 0, Math.PI * 2);
ctx.fill();
ctx.scale( 1/this.bigness, 1/this.bigness );
ctx.translate( -this.x, -this.y );
}
}
function rand( min, max ) {
return Math.random() * ( max - min ) + min;
}
for( var n = 0; n < 200; ++n )
step( false ); // just to have the thing already loaded
loop();
// boundary test
/*
ctx.fillStyle = ctx.strokeStyle = 'white';
ctx.fillRect( one.x, one.y, one.w, one.h );
ctx.beginPath();
ctx.arc( f0.x, f0.y, r2, 0, Math.PI * 2, true);
ctx.arc( f0.x, f0.y, r1, 0, Math.PI * 2, false);
ctx.fill();
ctx.beginPath();
ctx.arc( s0.x, s0.y, r2, 0, Math.PI * 2, true);
ctx.arc( s0.x, s0.y, r1, 0, Math.PI * 2, false);
ctx.fill();
*/
```

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