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                <script src="[email protected]/konva.min.js"></script>

<input id="slider" type="range" min="1" max="100" value="50">
<div id="container"></div>



                      body {
        margin: 40px;
        padding: 20px;
        overflow: hidden;
        background-color: #f0f0f0;
div {
  margin-top: 10px; 


                // This is info to control drawing the stars
const info = {
  count: 5,  // how many stars
  points: 5, // how many points on the stars - usually 5 !
  outerRadius: 40,  // outer radius of star 
  innerRadius: 20,  // inner radius of star
  position: {x: 40, y: 40},  // center of first star
  gap: 80,  // gap between stars
  percent: 100,   // percentage rating value
  colorInfoNeutral: {fill: 'silver'},
  colorInfoPositive: {
    fill: null,  // no solid color for this one.
    fillLinearGradientStartPoint: { x: 0, y: 0 },
    fillLinearGradientEndPoint: { x: 200, y: 200 },
    fillLinearGradientColorStops: [0, 'red', 1, 'yellow']       

// calculate the max width for the background racts
info.maxWidth = (info.innerRadius + * (info.count - 1);

// create a stage & layer for drawing
const stage = new Konva.Stage({
    container: "container", // id of container <div>
    width: 500,
    height: 500
  layer = new Konva.Layer(),
  starData = []; // array of points on the stars

// Function to calculate points of stars - we need these for the clip function so do not use Konva Star here,
// though this is the basis of the code in the Konva source that draws stars.
function starCalc(pos, numPoints, outerRadius, innerRadius ){
  const data = [];
  data.push({x: pos.x, y: pos.y - outerRadius})
  for (let n = 1; n < numPoints * 2; n++) {
    const radius = n % 2 === 0 ? outerRadius : innerRadius,
          x = radius * Math.sin((n * Math.PI) / numPoints),
          y = -1 * radius * Math.cos((n * Math.PI) / numPoints);
    data.push({x: pos.x + x, y: pos.y + y});
  data.push({x: data[0].x, y: data[0].y})
  return data;

// Now we use the star info to call the function to calculate the star points - no drawing yet ! 
for (let i = 0; i < info.count; i++){    
  const startPoints = starCalc({x: info.position.x + (i *, y: info.outerRadius}, info.points, info.outerRadius, info.innerRadius);

// Now create a group to contain the stars and the background rects.
// Important! - We create the clipping function using the star points - the stars become cutouts.
const group = new Konva.Group({
  draggable: true,
   clipFunc: function (ctx) {
      // Start only one path

      for (let i = 0; i < starData.length; i++){
        ctx.moveTo(starData[i][0].x, starData[i][0].y)
        for (let j = 1; j < starData[i].length; j++){
          ctx.lineTo(starData[i][j].x, starData[i][j].y)
        // Closing path, but not starting a new one

// make the background recs - we need 2 to show the different colours
const bgRect1 = new Konva.Rect({
  width: info.maxWidth,
  height: info.outerRadius * 2,

const bgRect2 = bgRect1.clone(info.colorInfoPositive);

// add the bg rects to the group - the positive color rect is on top, grey underneath
group.add(bgRect1, bgRect2);
// add the group to the layer

// add the layer to the stage

// A function to set the display correctly for the given rating, in percent 0 - 100
function setRatingPercent(percent){
  info.percent = percent;
  bgRect2.width(info.maxWidth *  info.percent / 100);

// Listener for the slider
$('#slider').on('input change', function() {

// Inially set the percentage to match the slider.