To spíš takhle:
anchor.setAttribute('href', 'data:text/html;charset=UTF-8,<html>' + encodeURIComponent(document.documentElement.outerHTML) + '</html>');
To spíš takhle:
anchor.setAttribute('href', 'data:text/html;charset=UTF-8,<html>' + encodeURIComponent(document.documentElement.outerHTML) + '</html>');