New: the prefer-reflect rule (fixes #2939)

[keithamus]

This PR adds a rule to warn when the user is using "effectively deprecated" methods - which Reflect.* replaces, as discussed in #2939. Fixes #2939.

As the docs/tests suggest, each section can be disabled - meaning the user can configure this how they need to, for example if they want to use reflect for all but the delete operator, then they can configure it as [2, "delete"].

Let me know if you need anything else from me to merge this.

Oh, also, so close!

[nzakas]

Apply only takes two arguments.

[nzakas]

Overall looks good. I would like to change the options to be more in line with how we've defined exceptions in other rules. I can see two possible options:

prefer-reflect: [2, { exceptions: [ "delete"]}]

prefer-reflect: [2, { delete: false}]

Kinda leaning towards the second, but could be convinced otherwise.

[michaelficarra]

@nzakas The second permits a tri-state with different falsey values (false and undefined) meaning different things. That's not a good interface in my opinion.

[keithamus]

I went more inline with a ruleset similar to no-restricted-modules. I'm happy to change it to the first example you show though.

[keithamus]

Rebased, fixed tests and changed rule options to be {exceptions: [...]} as per @nzakas instruction

[keithamus]

io.js travis build seems to be stuck, but I cant stop or restart it: https://travis-ci.org/eslint/eslint/jobs/71037738

[keithamus]

Failure is down to travis timing out trying to install iojs:

$ nvm install iojs
                                                                           0.4%
Your test run exceeded 120 minutes. 
One possible solution is to split up your test run.

Force pushed to trigger a new build. Should pass now.

[keithamus]

Oops, forgot to update docs in respect to change to using {exceptions:[]} syntax.

Docs updated now. This should be good to go.

[nzakas]

Please add JSDoc comments here

[keithamus]

Added jsdoc block for report function.

@nzakas is there anything else you'd like me to change?

[keithamus]

Fixed lint errors JSDoc.

[nzakas]

Can you use options instead of args?

options: [{exceptions: "apply"}]

You can leave off the initial 2, and any place with args: 2 can just be removed.

[keithamus]

All done @nzakas. Anything else?

[ilyavolodin]

I think there's an extra closing brace inside the array and one missing at the end of the line.

[ilyavolodin]

LGTM. Btw, awesome documentation!

[keithamus]

😄 thanks @ilyavolodin

[ilyavolodin]

Closing square brace is in the wrong place.

[nzakas]

Can you rebase?

[keithamus]

Rebased @nzakas

[ilyavolodin]

Thanks @keithamus for sticking with this!

[keithamus]

🎉