JSFiddle - React, Tailwind, and code Playground

HTML

<canvas width="100" height="100" id="canvas" class="canvas"></canvas>
<canvas width="100" height="100" id="canvas2" class="canvas" style="position: absolute; left: 10px; top: 10px;"></canvas>

JavaScript

var canvas = document.getElementsByClassName('canvas');

for(var i=0,l=canvas.length; l>i; i++)
{
    var ctx = canvas[i].getContext('2d');
    ctx.arc(50, 50, 50, 0, Math.PI*2, false,false);
    ctx.stroke();
}
//var ctx = canvas[0].getContext('2d');
//ctx.arc(50, 50, 50, 0, Math.PI*2, false,false);
//ctx.stroke();
//ctx = canvas[1].getContext('2d');
//ctx.arc(50, 50, 50, 0, Math.PI*2, false,false);
//ctx.stroke();


//var canvas = document.getElementById('canvas2');
//var ctx = canvas.getContext('2d');
//ctx.arc(50, 50, 50, 0, Math.PI*2, false,false);
//ctx.stroke();