Markup Improver
This tool tries to improve HTML markup and usage. Also gives you some statistics about external stylesheets and scripts references.

• Logs total number of external Stylesheets
• Logs total number of external Javascript files
• Warns about inline styles
• Warns about missing document language
• Warns about missing document charset meta
• Warns about missing or referencing wrong HTML elements from 'href' attributes of anchors
• Warns about Javascript code in document HEAD sections
• Warns about deprecated tags and attributes in HTML5 document type

Install from npm

npm i htmlimprover

Include the module and initialize it wherever you want to get hints about the HTML markup.

import * as HTMLImprover from 'htmlimprover';

HTMLImprover.ScanHTML();

For apps that aren't using Node modules, there is also a vanilla version(HTMLimprover.vanilla.js).
Include the script at the end of your document and call the ScanHTML function.