SOURCE

function drawRect(cxt,x,y,width,height,fillColor,borderWidth,borderColor){
  cxt.beginPath();
  cxt.rect(x,y,width,height);
  
  cxt.lineWidth = borderWidth;
  cxt.strokeStyle = borderColor;
  cxt.fillStyle = fillColor;
  
  cxt.fill();
  cxt.stroke();
}

var canvas = document.getElementById("canvas");
canvas.width = 700;
canvas.height = 700;
var context = canvas.getContext("2d");
let x = y = 50;
let width = height = 300;
while (width>0)
  {
   width -= 10;
   height -=10;
   x += 5;
   y += 5;
    drawRect(context,x,y,width,height,'#000',2,'#fff')
  }

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