JSFiddle - React, Tailwind, and code Playground

HTML

<body  onload="init()">
  <canvas id="myCanvas" width="400" height="150"></canvas>
</body>

JavaScript

function init() {
  var c = document.getElementById('myCanvas');
  var  ctx = c.getContext('2d');
      draw(ctx);
}

function draw (ctx) {
  ctx.fillStyle = '#f00';
  ctx.fillRect(30,30, 50,50);
}