Use modern JS in app.js of project templates

[samajammin]

Summary

Refactor app.js files to use modern syntax - const/let vs. var & async/await.

Motivation

• Demonstrate the Ethereum stack is up to date with latest development approaches
• Reduce boilerplate of callbacks so users can focus on the web3 logic

Describe alternatives you've considered

• Add support for JS frameworks #243 would also replace the existing app.js code of templates

Additional context

[nt1-8]

Hey @samajammin , are you accepting PRs for either of this or #243 ?
If so, I'd be happy to try submitting a PR using either approach.

I think I could make pretty quick work of updating the templates to use React, if that's a library that you all would be happy with using.

I'd also be happy to just start out by updating the app.js files to use more modern JS syntax, now that #228 #207 are just about done.

[samajammin]

Thanks again @nathan-lapinski! I believe the team would welcome additional PRs 😄

I think I could make pretty quick work of updating the templates to use React, if that's a library that you all would be happy with using.

That's certainly our vision (see #243). If you think it'd be quick work, I'd say go for it! Otherwise I think this issue to update to more modern JS would be a great start.

[javier-tarazaga]

Hi @nathan-lapinski!

All contributions are always more than welcome :) Originally we thought of that implementation as codesanbox/stackblitz do it, by adding support to npm packages in the FE. Said this, this can be a draconian task to do. Any other way which can get us one step closer to support any FE frameworks like React, Vue, Angular, etc is always more than welcomed.

[nt1-8]

Thanks @samajammin @javier-tarazaga !! I will start to look into this. I might just start with updating the app.js files to use more modern JS, since that should be a relatively quick win, and would be independent of any framework.

After that, I'd definitely like to look into #243 more 😄