Thank you for your post. I think it's should be helpful.
In my practice I visit these sites:
1. Stackoverflow (it's a champ).
2. w3school.com - you can find many simple examples and explanations.
3. Bootstrap 3 - in my practice I'm using this framework for developing.
4. Official docs: mdn, Google Maps API and so on.
5. codecademy - it's beacuse some difficult thing are well explained in a simple way.
6. ccs-tricks - you can find many interesting info.
7. can i use - provides up-to-date browser support tables for support of front-end web technologies on desktop and mobile web browsers.
I don't want to say that this list programmer should visit every day but these websites always helped me in web developing and I hope can be useful for someone.