I just started to use js2-mode in Emacs, and I found some variables like js2-global-externs and js2-additional-externs. The doc string says it is "A list of any extern names you'd like to consider always declared."
I don't understand what "extern" means here. I only knew the "extern" keyword in C, so I started to discover what "extern" means. I searched JavaScript extern/Ecma-262 extern/web browser extern but didn't get anything that looked promising. Can anyone point me in the right direction?
The extern keyword has nothing to do with JavaScript. It's some configuration on which js2-mode relies on to define the language.
For instance, I believe that you could add your own global variables js2-global-externs so that they get recognized.
Have a look at this file https://code.google.com/p/js2-mode/source/browse/trunk/js2-externs.el?r=57