The GoTo definition feature does not seem to be working with variables. I see a couple of posts regarding this in C/C++ but none in JS
A top level declaration like
let bar = 5;
does not bring up any matches when using Goto definition and typing ‘bar’
but a function definition like
let foo = () => {}
does match.
I was on build 3114 but then downgraded to 3103 since 3114 had a problem with finding function definitions in ExtJS class definitions
I saw in another post that the Babel plugin can mess with the Goto definitions and so I upgraded to build# 3114 and removed the Babel plugin. I do see functions defined in ExtJS classes now being populated in the Cmd-R list, so that’s great.
But I still do not see any variable definitions being listed 
This is almost certainly a bug in the JavaScript mode. You should file a bug here: https://github.com/sublimehq/Packages/issues Be sure to include some reproducing snippets.
We don’t index variables in any of the default packages. We index functions, classes, methods, structs, traits, etc. In some languages we index constants.