JSFiddle - React, Tailwind, and code Playground

JavaScript

var canvEl = document.createElement("canvas");
canvEl.style.position = 'absolute';
canvEl.style.top = '0px';
canvEl.style.left = '0px';
canvEl.style.width = "200px";
canvEl.style.height = "200px";
canvEl.id = "mycanvas";
alert(canvEl);
        
document.body.appendChild(canvEl)
    
var canvEl2 = document.getElementById("mycanvas");
alert(canvEl2);
var canvCTX = canvEl2.getContext("2d");
alert(canvCTX);
canvCTX.fillRect(0,0,1000,1000);