Add language support for JavaScript

[zhengbli]

Until now this plugin only handles .ts files and .tsx files. This PR adds supports for .js files and .jsx files as well.

[batusai513]

Any updates on this one?

[idiotWu]

I think some key trigger bindings should also be adjusted for JavaScript files, eg:

{
  "keys": ["("],
  "command": "typescript_signature_popup",
  "context": [
-      { "key": "selector", "operator": "equal", "operand": "source.ts, source.tsx" },
+      { "key": "selector", "operator": "equal", "operand": "source.ts, source.tsx, source.js, source.jsx" },
      { "key": "paren_pressed" }
  ]
}

Besides, I'm just wondering if this PR will be merged soon 😅 . Type completion for JavaScript files works perfectly in vscode, so I (and many other users) are looking forward to use this feature in sublime.

[james2doyle]

Since the issue seems to have gone stale, I had to turn to the Sublime LSP plugin and a different language server to get plain .js files working properly.

You can read more about how I got this working on the LSP Plugin repo.

[ryanolsonx]

Ping

[james2doyle]

I think this is closed now due to #620