JSFiddle - React, Tailwind, and code Playground

HTML

<canvas id='canvas'></canvas>
<canvas id='buffer'></canvas>

CSS

html, body {
    background-color:#eaeaea;
}
canvas{
    position: absolute;
    top: 0px;
    left: 0px;
}

#buffer{
    left: -9999px;
}
}

JavaScript

// Canvas and Buffers
var canvas = document.getElementById('canvas');
var buffer = document.getElementById('buffer');
var ctx = canvas.getContext('2d');
var buffer_ctx = buffer.getContext('2d');

// sizing
canvas.height = window.innerHeight;
canvas.width = window.innerWidth;

buffer.height = window.innerHeight;
buffer.width = window.innerWidth;

// mask image
var mask = new Image();
mask.onload = function () {
    drawBuffer();
}

mask.src = 'http://drewdahlman.com/experiments/masking/highball_mask.png';

function drawBuffer() {
    buffer_ctx.beginPath();
    buffer_ctx.rect(0, 256, 256, 75);
    buffer_ctx.fillStyle = "#c65127";
    buffer_ctx.fill();

    buffer_ctx.beginPath();
    buffer_ctx.rect(0, 226, 256, 25);
    buffer_ctx.fillStyle = "#f5f4f0";
    buffer_ctx.fill();

    buffer_ctx.beginPath();
    buffer_ctx.rect(0, 186, 256, 35);
    buffer_ctx.fillStyle = "#222";
    buffer_ctx.fill();
    
    var image = buffer.toDataURL("image/png");
    var img = new Image();
    img.onload = function(){
        buffer_ctx.clearRect(0,0,buffer.width,buffer.height);
        ctx.drawImage(mask,0,0);
        ctx.globalCompositeOperation = 'source-in';
        ctx.drawImage(img,0,0);
    }
    img.src = image;
}