No. By visiting their site, you say that this is all okay. On top of these things, W3Schools has also engaged in some sketchy SEO tactics. (http://www.itworld.com/software/261486/w3schools-hubbub-over...)

I refuse to use the site. This behavior should not be encouraged. If you would like an alternative, I highly recommend the Mozilla Developer Network. (https://developer.mozilla.org/en-US/)