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"
  }
}]

Advocate

Answer 1

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).

Bennett

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? – Advocate

@MaxTravis - The rule is for the last property, not each line. You have no choice about the commas between properties. – Bennett

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 – Advocate

@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. – Bennett

Ouch, I understood you now. Sorry for that, I just still a little bid confused after migration from .js to .ts ! Thanks! – Advocate

Answer 2

I solved this in my tslint.json as following:

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

Broncobuster

Answer 3

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

Lamar

I also like it cause when you are copying and pasting and changing lines order the comma there helps a lot! – Photoplay