JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container"></div>
<script src="https://dl.dropboxusercontent.com/u/47067729/konva.min.js"></script>

CSS

#container {
    border: 1px solid green;
    background-color: lime;
}

JavaScript

console.clear();

var history = new Array();

var imageObj = new Image();
var img = null;

stage = new Konva.Stage({
    container: 'container',
    width: 600,
    height: 400
});
layer = new Konva.Layer();
stage.add(layer);

var rect = new Konva.Rect({
      x: 30,
      y: 30,
      width: 438,
      height: 300,
      fill: 'yellow'
    });
layer.add(rect);

var canvas = document.createElement('canvas');
var context = canvas.getContext('2d');



var circle = new Konva.Circle({
    x: 0,
    y: 0,
    radius: 40,
    opacity: 0.7,
    fill: '#ff5e0a',
    stroke: '#d95009',
    strokeWidth: 1,
    draggable: true
});
layer.add(circle);


circle.on('dragmove touchmove', function (e) {
    erase(e.evt.clientX, e.evt.clientY, circle.radius(), img.x(), img.y());
});


imageObj.onload = function () {
    canvas.width = imageObj.width;
    canvas.height = imageObj.height;
    context.drawImage(imageObj, 0, 0, imageObj.width, imageObj.height);
    
    img = new Konva.Image({
        x: 30,
        y: 30,
        image: canvas
    });

    layer.add(img);
    
    circle.moveToTop();
    layer.draw();
};

imageObj.crossOrigin = "anonymous";
imageObj.src = "https://dl.dropboxusercontent.com/u/47067729/darth-vader.jpg";


function erase(absX, absY, radius, imgX, imgY) {
    var x = 0;
    var y = 0;
    
    // set pointer
    circle.x(absX);
    circle.y(absY);
    
    x= absX - imgX;
    y= absY - imgY;
    
    context.globalCompositeOperation = 'destination-out';
    context.globalAlpha = 0.118;
    context.beginPath();
    context.arc(x, y, radius, 0, 2 * Math.PI);
    context.fill();
 
    layer.draw();
}