Div convert to image or base64 with JS

Question

I need to convert my div in image or base64 using JS.

I found the html2canvas library on the Internet that performs this procedure, but always displays the error:

Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.

When I add the element "canvas" it shows no error, but does not generate the base64 and neither image

I did the code with and without the canvas, Find the code below.

With Canvas

<script type="text/javascript">  
  var canvas = document.createElement('canvas');
  var map = document.getElementById("mapa");

  canvas.appendChild(map);

  html2canvas(canvas, { 
    useCORS: true,
    onrendered: function(canvas) {
    var dataUrl= canvas.toDataURL("image/png");
    console.log("Imagem - dataurl",dataUrl);
    var encodedPng = dataUrl.substr(dataUrl.indexOf(',') + 1, dataUrl.length);
    var decodedPng = Base64Binary.decode(encodedPng);
  }});

Without Canvas

<script type="text/javascript">     
  var canvas = document.getElementById("mapa");
  html2canvas(canvas, { 
    useCORS: true,
    onrendered: function(canvas) {
    var dataUrl= canvas.toDataURL("image/png");
    console.log("Imagem - dataurl",dataUrl);
    var encodedPng = dataUrl.substr(dataUrl.indexOf(',') + 1, dataUrl.length);
    var decodedPng = Base64Binary.decode(encodedPng);
  }});

I appreciate any help, as it already does not know what to do to accomplish this task!

Tks,