JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://parall.ax/parallax/js/jspdf.js"></script>
<canvas id="myCanvas" width="578" height="200"></canvas>
<button id="download">download</button>

JavaScript

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

// draw a blue cloud
context.beginPath();
context.moveTo(170, 80);
context.bezierCurveTo(130, 100, 130, 150, 230, 150);
context.bezierCurveTo(250, 180, 320, 180, 340, 150);
context.bezierCurveTo(420, 150, 420, 120, 390, 100);
context.bezierCurveTo(430, 40, 370, 30, 340, 50);
context.bezierCurveTo(320, 5, 250, 20, 250, 50);
context.bezierCurveTo(200, 5, 150, 20, 170, 80);
context.closePath();
context.lineWidth = 5;
context.fillStyle = '#8ED6FF';
context.fill();
context.strokeStyle = '#0000ff';
context.stroke();

download.addEventListener("click", function() {
  // only jpeg is supported by jsPDF
  var imgData = canvas.toDataURL("image/jpeg", 1.0);
  var pdf = new jsPDF();

  pdf.addImage(imgData, 'JPEG', 0, 0);
  var download = document.getElementById('download');

  pdf.save("download.pdf");
}, false);