JSFiddle - React, Tailwind, and code Playground

HTML

<canvas width="200" height="200"></canvas>
<canvas width="200" height="200"></canvas>

JavaScript

var canvasArr = document.querySelectorAll("canvas");
var ctx = [];
var i = canvasArr.length;
while(i--){
	ctx[i] = canvasArr[i].getContext("2d");
}

ctx[0].fillStyle = "white";
ctx[0].fillRect(0,0,200,200);
ctx[0].shadowBlur = 20;
ctx[0].shadowColor = "black";
ctx[0].fillRect(50,50,100,100);

ctx[1].fillStyle = "black";
ctx[1].fillRect(0,0,200,200);
ctx[1].shadowBlur = 20;
ctx[1].shadowColor = "white";
ctx[1].fillRect(50,50,100,100);