Adopt Prettier

[jasonLaster]

It would be nice to adopt prettier across devtools and perhaps m-c globally.

Benefits

• it will provide a consistent set of styles for the project that can be overridden can via eslint
• it will simplify our eslint config
• it will be like James 🤗never left
• it helps contributors and code reviews
• the debugger has been using it for the past two years and it is great
• it has good editor / vcs integrations
• When we discussed this in the tuesday node meeting, Dan Mosedale mentioned that he and Mark Banner discussed adding prettier globally to be consistent with C++ clang. Adding prettier for devtools would be a good test case for what prettier across MC would look like.

Process changes

• We would run prettier once to update the devtools files
• We would update the devtools eslint config to include the eslint-prettier plugin.
• At that point, ./mach lint will begin picking up the regressions and reporting them on try as well.

[juliandescottes]

When we discussed this in the tuesday node meeting, Dan Mosedale mentioned that he and Mark Banner discussed adding prettier globally to be consistent with C++ clang. Adding prettier for devtools would be a good test case for what prettier across MC would look like.

I am totally in favor of enforcing formatting for all our JS. Whether it's prettier or clang (I think some people use clang for js formatting as well?) I don't mind. I would only ask that we don't diverge from the rest of the style used in the JS codebase in mozilla-central. But according to your last edit this is part of a global effort to add formatting everywhere in m-c, so it sounds great :)

[gregtatum]

Yes please. This has been a huge win for the Firefox Profiler, and simplifies the code review process. I really appreciate the clang format for the C++ side of things in Gecko.

[zoepage]

I love prettier and would be in favor, especially as we can lint JS and CSS here.

[victorporof]

I've been investigating this a considerable amount the past month or so, and have a lot of data to share here. Some conversations in this document: https://docs.google.com/document/d/1P_Wcb9VwLN8GpvyHq-_2XNcbHWTHhUfu_JYgadS-7vY/edit#heading=h.jrzw5jojmbmk

I'll pop by to chat about it :)