Proposal: Add "consistent" option to array-element-newline

[robertrossmann]

Tell us about your environment

• ESLint Version: 4.9.0
• Node Version: 8.7.0
• npm Version: 5.4.2

I would like to propose to add a third, new option, consistent, to the rule array-element-newline.

Expected behaviour

Given 'array-element-newline': ['warn', 'consistent'], a newline would be required between all array elements if any of the elements are placed on a separate line.

Good

// 'array-element-newline': ['warn', 'consistent']
const arr = [1,2,3]
const arr = [
  1, 2, 3
]
const arr = [
  1,
  2,
  3,
]

Bad

// 'array-element-newline': ['warn', 'consistent']
const arr = [
  1, 2,
  3,
]

Autofix

If implemented, the autofix would separate all elements onto a separate line if any of the elements are on a separate line. The autofix would never put all elements into a single line.

Current behaviour

The rule currently only supports only:

• no newlines between elements
• num elements-based decision about elements placement
• all elements on their own line

---

This follows the idea recently implemented in #9206 for array-bracket-newline and is tangentially related to #9054.

[platinumazure]

I'll support this. Thanks for the suggestion!

[robertrossmann]

Thanks @platinumazure! I wonder if I can start working on a PR or we need more votes here to accept this...? Is there anything I can do to further this?

[ilyavolodin]

@robertrossmann Every proposal requires 3 members of the team to support it, and one more member to champion it. I'll support this proposal. @eslint/eslint-team anyone else wants to support this?

[aladdin-add]

I like this option! 👍

[platinumazure]

I'll champion. Just needs one more 👍 from the @eslint/eslint-team!

[platinumazure]

@eslint/eslint-team Can we get one more 👍 for this proposal? If not, I'll have to close. Thanks!

[kaicataldo]

Apologies for the delay. This is now accepted.