SOURCE

console 命令行工具 X clear

                    
>
console
var paper = Raphael(0, 0, 600, 600);

// Creates circle at x = 50, y = 40, with radius 10



var n=0;

var m=0;

document.onkeypress=function(){
  for(var i=0;i<1;i++)
    {
      var x = Math.random()*400+100;
      var y = Math.random()*400+100;
      var circle = paper.circle(x, y, 4);
      //circle.attr("fill", "#f00");
      var d = Math.sqrt((x-300)*(x-300)+(y-300)*(y-300));
      n++;
      if(d<200)
        {
          m++
        }
      console.log(m,n,m/n*4);
    }
  var circle = paper.circle(300,300,200);
}

<canvas id="canvas"></canvas>