iFrame to image using domvas

iframeToImage.js

var canvas = document.getElementById('canvas-id');
var context = canvas.getContext('2d');
var idoc = document.getElementById('iframe-id').contentWindow.document.body;

domvas.toImage(idoc, function() { 
   context.drawImage(this, 0, 0, width, height);
   
   // Download
   var rawImageData = canvas.toDataURL("image/png;base64");
   rawImageData = rawImageData.replace("image/png", "image/octet-stream");   
   document.location.href = rawImageData;
}, width, height);