Create base64 buffer and get extension

base64-buffer-ext

const image = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAABH0lEQVRYhWN0jUr5zzCAgGkgLWdgYGBgoUTzrqWzKXYA44iPglEHjDpg1AGjDhh1wIA7gKLaEBewNjFkCPf1YPj05StDTfckrGpignwZgj1daRMCAe7ODKqK8gysLNj9Z6qvw+BmZ8Wwafd+2jigtLWH4dL1WzjlzQ30GH7/+cOw69Ax2kQBNmCko8VQkp7AcOLcJQZJMRGGT5+/Mjx98ZJ+ifDclWsMUbllDJPmL2FgYmJi+PXrFwMDwwDlgn///sHZA+KApy9eMQgK8DNwcrAPjANOXrjEwMHOxhDh58XArKxr1EBtCzorixgMdTQZJMVEGXTUVRn2HDnOYKSjxdBbW8ogLSHOsH7HHgY+Hh6GYC/X0VbxqANGHTDwDgAA+4tGGj9PrTsAAAAASUVORK5CYII='
const regex = /^data:.+\/(.+);base64,(.*)$/;

const matches = image.match(regex);
const extension = matches[1];
const data = matches[2];
const buffer = new Buffer(data, 'base64'); // write, stream, something ...