JSFiddle - React, Tailwind, and code Playground

HTML

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

JavaScript

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
ctx.fillStyle="rgba(50, 255, 50, 0.607843137254902)"
ctx.rect(0, 0, 100, 100);
ctx.fill();

console.log(ctx.getImageData(0, 0, 1, 1).data);