var canvas = new fabric.Canvas('c');

var circle = new fabric.Circle({
  radius: 120, fill: 'green', left: 20, top: 0
});
var triangle = new fabric.Triangle({
  width: 120, height: 130, fill: 'blue', left: 0, top: 00
});

canvas.add(circle, triangle);

canvas.renderAll();

canvas.bringToFront(circle);