JS1k: The JavaScript code golfing competition

c=document.getElementById("c");var s=400,D=0.3,Z=255,R=Math.random,i;c.width=c.height=s;var X=c.getContext("2d"),h=X.getImageData(0,0,s,s),t=h.data,U=0;for(i=0;i<s*s*4;i+=4){if(R()<D){t[i+2]=Z;if(R()<0.0003){t[i]=Z}else{U++;t[i]=35}t[i+1]=142}else{t[i]=t[i+1]=t[i+2]=0}t[i+3]=Z}X.putImageData(h,0,0);var W=!!1,a,b,c,d,x,y,B,C,T,K,L,M,N,g=function(e){if(t[e+2]==Z){if(t[e]!=Z)U--;t[e]=t[e+1]=Z}},Q=setInterval(function(){for(x=0;x<s;x+=2){for(y=0;y<s;y+=2){d=((L=((K=(x+W)%s)+1)%s)+(N=((M=(y+W)%s)+1)%s)*s)*4;a=(K+M*s)*4;B=b=(L+M*s)*4;C=c=(K+N*s)*4;if(t[a]==Z||t[b]==Z||t[c]==Z||t[d]==Z){g(a);g(b);g(c);g(d)}else{if(R()<0.5)B=c,C=b;for(i=0;i<3;i++){T=t[a+i];t[a+i]=t[B+i];t[B+i]=t[d+i];t[d+i]=t[C+i];t[C+i]=T}}}}W=!W;X.putImageData(h,0,0);if(!U){clearInterval(Q)}},100);

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

Original source not submitted