I tried to search for a JavaScript reference, but there's none available. The best two suggested sources are MDN (Mozilla Developer Network) and ECMA (https://262.ecma-international.org/12.0/)
Why?
It's not like there is an official JavaScript release. All the browsers have made their own JavaScript engine - some are using the same though. But especially Internet Explorer has its own version that doesn't support a lot of what the other browsers support, making it very difficult to make a general JavaScript reference.
Edit:
While I know there is an official ECMA standard and development team, my point is that it doesn't really matter as long as browsers (Internet Explorer) doesn't live up to it. At the end of the day, clients want JavaScript to work for Internet Explorer too. They won't care about the ECMA standards, they just want it to work. This is where JavaScript libraries come into the picture, but that's another story.
It's the same issues with HTML and CSS, we can't use these tools for active development until:
Edit2:
Internet Explorer is getting close to the grave with the new browser project from Microsoft: Edge. This, however, doesn't really change the overall picture. We still have a lot if different browsers we need to support. Developers are constantly trying to push the boundaries of what's possible. This means that we often have this issue, some browser version we want to support doesn't support some feature of the standard (which usually is a bit fluid), which means we need to make some workaround or use frameworks that implement the missing built in features.