Mandelbrot Set

The Mandelbrot set is one of the most famous fractal.
The mandelbrot set is defined by the set of complex numbers c for which the complex numbers of the sequence z_n remain bounded in absolute value. The sequence z_n is defined by:
$$ z_0 = 0 $$ $$ z_n+1 = z_n^2 + c $$ where c is a complex number and z_n is the nth complex number in the sequence.

Code

            
    elem=document.querySelector(".example-container");
    setCanvas(elem);
    
    function draw() {
            
        clearCanvas();
        w=WIDTH;
        h=HEIGHT;
        for(i=0;i<w;i+=1){
            for(j=0;j<h;j+=1){
                var a= mapRange(i,0,w,-2,1);
                var b= mapRange(j,0,h,-1.5,1.5);
                var ca=a;
                var cb=b;

                var n=0;
                while(n<100){

                    var aa=a*a-b*b;
                    var bb=2*a*b;
                    a=aa+ca;
                    b=bb+cb;
                    if(a+b>4){
                        break;
                    }
                    n++;
                }

                var c=mapRange(n,0,100,0,360);

                if(c>20){
                new rect(i,j,2.5,2.5,`hsl(${c},100%,50%)`,1,`hsl(${c},100%,50%)`,0,'top-left',0);
                }

            }
        };

//        requestAnimationFrame(draw);

    }
        
    
    draw();