I have a website that is pretty demanding in regards to required browser features. Currently, the site does not indicate this in any way to visitors when they access it with an old browser.

I want to change that, and I am wondering what is the best way to do that. Those are the concerns I have:

  • I don't want to check for the user agent and rather check for the required featues (websockets, certain CSS features)
  • I want to display a helpful message to point users to an upgraded browser. This is mostly a UX thing.
  • I dont want to confuse any search engine crawlers by showing them the message to upgrade their browsers.

What are good practices for doing so?

2 Answers 2


You want Modernizr, a feature based detection library. Combine that with Browsehappy.org, and you should be able to detect when someone is on a browser that can't support your website, and they'll be able to easily either upgrade or move to a better browser.


As for feature detection, Modernizr is the an open source JavaScript library that is widely used and has a reputation for being eficient.

On the message to upgrade the browser it's a good practice to point to a site where they can chose modern browsers. PLease note some browsers have specific system requirements like for example a minimum operating system version. For example some browsers will not work with Windows XP, Vista or old versions of Mac OS or Linux.

To avoid confusing search engine crawlers you can use the rel="nofollow" attribute in anchor tags and googleoff + googleon comment tags before and after the update your browser content.


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