Use babel to transpile the workbox-build codebase?

[MaxLeiter]

Library Affected:
workbox-build

Browser & Platform:
all browsers

Issue or Feature Request Description:
Currently making a PR, should be as easy as throwing in a 'use strict';

Ref: https://travis-ci.org/thelounge/lounge/jobs/251861458
and thelounge/thelounge#1317

[jeffposnick]

Thanks for pointing that out! The intention is to get support node 4 for workbox-build, though we obviously haven't done a great job of testing that.

While we could approach this via adding in 'use strict';' throughout the individual modules, I wanted to see how @gauntface & co. felt about running the workbox-build project through babel with babel-present-env set up for node 4.

There are a number of times that I've wanted to use, e.g., async/await or spread operators when working on the workbox-build codebase, but didn't, because of legacy node support.

[MaxLeiter]

Sounds good to me.

[gauntface]

Personally I hate having to transpile anything just to run in a baseline environment so I'd rather just accept use strict.

There is a bigger question of what our support matrix should be. Should it be current stable and latest version? or should be follow the same as node's schedule where node 4 is in maintanence? https://github.com/nodejs/LTS

[jeffposnick]

The initial impetus behind a minimum of node 4 was to match what create-react-app required, on the assumption that we will try to integrate with them at some point. It turns out c-r-a has since switched to requiring node 6: facebook/create-react-app#1897

That being said, since we can easily resolve node 4 support with minimal extra effort, I'm fine with keeping 4 as a minimum, at least until April 2018.

We're going to need use strict throughout workbox-build and workbox-cli, in that case.

[MaxLeiter]

use strict is already present throughout workbox-cli and part of workbox-build. It's just missing from some files. Will update #670 to encompass all the files that require it.

[MaxLeiter]

Fixed as of #670