prefer-arrow/prefer-arrow-function: prefer arrow to allow top level named functions as default

[kbrilla]

🚀 Feature Request

Currently migration will just output notice that top level named functions are disallowed by the plugin, but default tslint behaviour is to allow them. I think default migration should enable allowStandaloneDeclarations configuration parameter of the prefer-arrow/prefer-arrow-functions rule to match tslint rule behaviour.

Existing Behavior

top level function declarations allowed as default

Change Proposal

  "prefer-arrow/prefer-arrow-functions": [
          "error",
          {
            "allowStandaloneDeclarations": true
          }
        ]

as default migration

[KingDarBoja]

Did I miss something? AFAIK, the TSLint rule states:

Disallows traditional (non-arrow) function expressions.

And provides an option to allow named functions (allow-named-functions), which I believe is for top-level named functions.

[kbrilla]

I'm pretty sure the TsLint rule didn't report such functions, as I had no errors like this while linting. After conversion EsLint is reporting them so they have to be a difference in their behaviors.

[KingDarBoja]

i am still not 100% sure about the correct behaviour, tried to understand the differences following this issue at the plugin repository but based on this one, it seems you are right, so feel free to go ahead and make a PR 🚀

[JoshuaKGoldberg]

Just following up, I tried out npx tslint index.ts with:

// tslint.json
{
  "rules": {
    "only-arrow-functions": true
  }
}

// index.ts
function myFunc() {

const myFunc = function () {}

...and TSLint did complain by default:

$ npx tslint index.ts
index.ts:1:1
ERROR: 1:1   only-arrow-functions  non-arrow functions are forbidden
ERROR: 3:16  only-arrow-functions  non-arrow functions are forbidden