For anyone having issues in IE:
Please upvote the answer here by Yetti: saving canvas locally in IE
dataURItoBlob = function(dataURI) {
var binary = atob(dataURI.split(',')[1]);
var array = [];
for(var i = 0; i < binary.length; i++) {
array.push(binary.charCodeAt(i));
}
return new Blob([new Uint8Array(array)], {type: 'image/png'});
}
var blob = dataURItoBlob(uri);
window.navigator.msSaveOrOpenBlob(blob, "my-image.png");