Code style update (const, arrow functions)

[tuchk4]

Started here - #1433 (comment)

(only for packages/react-scripts)

• If arrow functions are already used maybe switch others functions to arrow ?
• Same for var -> const. For example:
  • test.js - only const is used
  • start.js - only var is used
  • webpack.config.prod.js both var and constare used

[gaearon]

Let's do what I suggested there for global CLI too, and move all the code except the Node version check into a separate file that would be lazily required. This way we can use modern syntax there without screwing up the version check message.

[tuchk4]

• (packages/react-scripts) switch normal functions to arrow
• (packages/react-scripts) switch var to const
• (packages/create-react-app) split into two scripts - index.js with node version check that should be available for node 0.12 and create-react-app.js (suggest your script name) with modern syntax that is required from index.js after node version check

correct?

[gaearon]

Yes, although I'd only switch to arrows where it helps readability. I'd leave top level functions as named declarations.