JS1k: The JavaScript code golfing competition

d=document;c.setAttribute("style","float:left;margin:9px");e=d.createElement("div");e.innerHTML='<a target="_blank" href="http://x.vu/237908">L-system\u02c0</a>:<br><textarea id="l" rows=6 cols=34>iters:5\nangle:45\nstart:"X"\nX:"+ff++f++f--f++f++ff"\nf:"fff[-ffX][+fX]"</textarea><br><input type="submit" onclick="g()">';b.appendChild(e);
g=function(){with(Math){w=c.width=c.height=500;s=eval("({"+d.getElementById("l").value.trim().replace(/\n/g,",")+"})");t=s.angle/180*PI;q=s.start;for(i=0;i<s.iters;++i){m="";for(j=0;j<q.length;)r=s[h=q[j++]],m+=r?r:h;q=m}u=function(l,k){S=[];x=y=p=i=0;for(eval(k);i<q.length;)h=q[i++],"+"==h?p+=t:"-"==h|"\u2212"==h?p-=t:"["==h?S.push([x,y,p]):"]"==h?(o=S.pop(),x=o[0],y=o[1],p=o[2],eval(k)):h==h.toLowerCase()&&(x+=cos(p),y-=sin(p),eval(l))};A=B=C=D=0;u("A=min(x,A);B=max(x,B);C=min(y,C);D=max(y,D)",
0);P=B-A;Q=D-C;f=min(w/P,w/Q);with(a)strokeStyle="#C03",scale(f,f),translate(-A-P/2+w/2/f,-C-Q/2+w/2/f),lineWidth=1/f,beginPath(),u("a.lineTo(x,y)","a.moveTo(x,y)"),stroke()}};g();

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

/*
The script executes given L-system code and generates fractals on the screen. This is the Hilbert curve:

iters: 7
angle: 90
start: "L"
L: "-Rf+LfL+fR-"
R: "+Lf−RfR−fL+"

"iters" if the number of iterations. "angle" is the turning angle in degrees. "start" is the initial axiom. Other lines are the rewrite rules. Supported operators are +− for turning, lowercase letters for drawing, and [] for push and pop.

For more examples, see: http://web.itu.edu.tr/~aygunes/eser/Computer/LsystemFractalGeneratorForJS1K
*/

d = document;

c.setAttribute("style", "float:left;margin:9px");
e = d.createElement("div");
e.innerHTML = '<a target="_blank" href="http://x.vu/237908">L-systemˀ</a>:<br>'
		+ '<textarea id="l" rows=6 cols=34>iters:5\nangle:45\nstart:"X"\nX:"+ff++f++f--f++f++ff"\nf:"fff[-ffX][+fX]"</textarea><br>'
		+ '<input type="submit" onclick="g()">'
b.appendChild(e);

g = function () { // go
	with (Math) {
		// Clear and resize the canvas;
		w = c.width = c.height = 500; // width
		
		// Parse the L-system.
		s = eval("({" + d.getElementById("l").value.trim().replace(/\n/g, ",") + "})"); // lsystem
		t = s.angle / 180 * PI; // theta
		q = s.start; // sequence
		
		// Generate the sequence.
		for (i = 0; i < s.iters; ++i){
			m = ""; // temporary
			for (j = 0; j < q.length;) {
				r = s[h = q[j++]]; // rewrite, character
				m += r ? r : h;
			}
			q = m;
		}
		
		// Define the execute function.
		u = function (k, l) { // execute, line callback, move callback
			S = []; // stack
			x = y = p = i = 0; // x, y, alpha
			eval(l);
			for (; i < q.length;) {
				h = q[i++];
				h == "+" ? p += t
					: h == "-" | h == "−" ? p -= t
					: h == "[" ? S.push([x, y, p])
					: h == "]" ? (o = S.pop(), x = o[0], y = o[1], p = o[2], eval(l))
					: h == h.toLowerCase() ? (x += cos(p), y -= sin(p), eval(k))
					: 0;
			}
		}
		
		A = B = C = D = 0; // minX, maxX, minY, maxY
		u("A=min(x,A);B=max(x,B);C=min(y,C);D=max(y,D)", 0);
		
		P = B - A; // deltaX
		Q = D - C; // deltaY
		f = min(w / P, w / Q); // factor
		with (a) {
			strokeStyle = "#C03";
			scale(f, f);
			translate(
					-A - P / 2 + w / 2 / f,
					-C - Q / 2 + w / 2 / f);
			lineWidth = 1 / f;
			beginPath();
			u("a.lineTo(x,y)", "a.moveTo(x,y)");
			stroke();
		}
	}
}

g();