tslint - Missing trailing comma (trailing-comma) on the last line

Question

I cannot figure out why my tslint even want to see the trailing comma on the end of the last line in the objects? How can I set the ignore rule for the last line of the objects for example? Thanks.

Exemple:

  props = {
    prop1: 21, // good
    prop2: 2, // good
    prop3: false // error: [tslint] Missing trailing comma (trailing-comma)

  }

Rule for trailing-comma in my tsconfig.json:

"trailing-comma": [true, {
  "singleline": "never",
  "multiline": {
    "objects": "always",
    "arrays": "always",
    "functions": "never",
    "typeLiterals": "ignore"
  }
}]

score 34 · Accepted Answer · answered Sep 07 '18 at 08:20

34

You clearly have the rule enabled for multi-line objects:

"trailing-comma": [true, {
  "singleline": "never",
  "multiline": {
    "objects": "always",     // <==================
    "arrays": "always",
    "functions": "never",
    "typeLiterals": "ignore"
  }
}]

So...disable it by making that "never" (if you want to disallow commas there) or "ignore" (if you want to allow commas to be there or not, either way).

answered Sep 07 '18 at 08:20

T.J. Crowder

1,031,962
187
1,923
1,875

Oh, but in this case we shall to fully disable `trailing commas` for `object`, instead to make it disabled only for the last line in it. Is not? – Max Travis Sep 07 '18 at 08:23
1

@MaxTravis - The rule is for the last property, not each line. You have no choice about the commas *between* properties. – T.J. Crowder Sep 07 '18 at 08:24
Thank you, but to be clearly, if I set the `"objects": "always"` to `never` or `ignore` it will disable this tslint rule for whole object, that's incorrect... It will be: `props = { prop1: 21, prop2: 2 prop3: false }` - on the `prop2` must be an error in tslint – Max Travis Sep 07 '18 at 08:27
3

@MaxTravis - `prop2: 2 prop3: false` is **already** a syntax error. This rule has nothing to do with it. This rule is purely about a comma after the **last** property before the closing `}` on the object initializer. – T.J. Crowder Sep 07 '18 at 08:30
1

Ouch, I understood you now. Sorry for that, I just still a little bid confused after migration from .js to .ts ! Thanks! – Max Travis Sep 07 '18 at 08:48

score 1 · Answer 2 · edited Aug 14 '19 at 20:42

1

I solved this in my tslint.json as following:

"rules": { "trailing-comma": false }

edited Aug 14 '19 at 20:42

ejderuby

710
5
21

answered Aug 14 '19 at 15:43

M.Liscio

577
1
4
11

score 1 · Answer 3 · answered Dec 18 '20 at 15:54

1

Include trailing comma even in the last line is a good practice of having less merge conflict, although it looks weird.

answered Dec 18 '20 at 15:54

Yi Yang

85
2

I also like it cause when you are copying and pasting and changing lines order the comma there helps a lot! – Daniel Vilela Oct 17 '22 at 19:11

tslint - Missing trailing comma (trailing-comma) on the last line

3 Answers3