Google says don’t use JavaScript to generate a noindex tag in the original page code

Google updated its JavaScript SEO basics documentation to clarify that may skip rendering and JavaScript execution.

Google explains JavaScript execution on non-200 HTTP status codes

Google noted that if the HTTP status code is non-200 (for example, on error pages with 404 status code), rendering might be ...
InfoWorld

Opera working on faster JavaScript engine

Carakan, intended to be world's fastest JavaScript engine, will be released in as-yet-undetermined version of the Opera browser Opera is working on a JavaScript engine, called Carakan, which is ...