float rand(float n){return fract(sin(n) * 43758.5453123);}
float noise(float p){
float fl = floor(p);
float fc = fract(p);
return mix(rand(fl), rand(fl + 1.0), fc);
}
A Pen by Boomerang2055 on CodePen.
Source for js1k entry: http://js1k.com/2014-dragons/demo/1837