eslint/tslint behavior difference with comma-dangle

[danvk]

Bug Report (delete this for feature requests)

• TSLint version: 3.7.3
• TypeScript version: 1.8.9
• Running TSLint via: CLI

TypeScript code being linted

function f() {
  return [1, {
    a: 2,
    b: 2,
  }];
}

with tslint.json:

{
  "rules": {
    "trailing-comma": [
      true,
      {
        "multiline": "always",
        "singleline": "never"
      }
    ]
  }
}

Actual behavior

repro.ts[5, 3]: missing trailing comma

Expected behavior

(no error)

When I run this code through eslint with the following config:

{
  "rules": {
    'comma-dangle': [2, 'always-multiline'],
  }
}

it passes. But tslint wants me to write this instead:

function f() {
  return [1, {
    a: 2,
    b: 2,
  },];  // <---
}

which I don't think makes much sense. In fact, eslint complains about it:

repro.ts
  5:4  error  Unexpected trailing comma  comma-dangle

[unional]

Exactly the issue I have with this: https://github.com/palantir/tslint/blob/3.7.4/src/configuration.ts#L52

[adidahiya]

fair enough. we'd be open to a PR that adjusts the behavior here to align with ESLint.

[jkillian]

Hi all, please see #1145 and check if it does what you need (it should fix this).

[unional]

Interesting. and 👍