Enforces return statements in callbacks of array's methods (array-callback-return)

[feross]

ESLint just promoted this rule to their 'eslint:recommended' rule set, so it's probably pretty reliable. I want to check how much of the ecosystem this effects and consider enabling it.

Array has several methods for filtering, mapping, and folding. If we forget to write return statement in a callback of those, it's probably a mistake.

This rule enforces usage of return statement in callbacks of array's methods.

This rule finds callback functions of the following methods, then checks usage of return statement.

Array.from
Array.prototype.every
Array.prototype.filter
Array.prototype.find
Array.prototype.findIndex
Array.prototype.map
Array.prototype.reduce
Array.prototype.reduceRight
Array.prototype.some
Array.prototype.sort

https://github.com/eslint/eslint/blob/master/docs/rules/array-callback-return.md

[dcousens]

Yes.

[dcousens]

Though, I have used .some in the past to short-circuit a forEach loop

[feross]

@dcousens It's fine to use .some in that way. You're still using return in the function callback right?

[dcousens]

If we forget to write return statement in a callback of those, it's probably a mistake.

I misread it as if we forget to write return statement for those, indeed, you are right 👍

[feross]

About 7% ecosystem effect:

1..207
# tests 207
# pass  193
# fail  14

Examples of failures that I think are good errors to report:

    const tuples = this.stringTuples().filter((tuple) => {
      if (tuple[0] === protocols.names.ipfs.code) {
        return true
      }
    })

  tuples.map(tup => {
    const proto = protoFromTuple(tup)
    parts.push(proto.name)
    if (tup.length > 1) {
      parts.push(tup[1])
    }
  })

More marginal cases where more explicitness doesn't hurt:

    keys.some(function (key, i) {
      tasks[key](function (err, result) { each(key, err, result) })
      if (i === limit - 1) return true // early return
    })

    input.some(item => {
      if (typeof item === 'string') {
        opts.name = corePath.basename(item)
        return true
      } else if (!item.unknownName) {
        opts.name = item.path[item.path.length - 1]
        return true
      }
    })