Option to permit no-useless-return inside blocks

As discussed in https://github.com/airbnb/javascript/issues/1210, it will be great if no-useless-return offers an option to allow return inside blocks, to benefit consistency between blocks when using a useless return to quit the function execution at that point.

Here is an example:

async function f(p) {
  if (p === 'a') {
    // some lines of code
    await fn()
    
    return
  }
  
  if (p === 'b') {
    // some lines of code
    await fn()
    
    return
  }

  if (p === 'c') {
    // some lines of code
    await fn()
    
    return // <-- option to allow tihs one
  }
}

Having them separated by blank lines make it clearer and easy to maintain instead of having a big if-else if-else block.

Having this last useless return enforces consistency with other blocks and also, if you add a new block below, you will not have to modify the (until now) last one block to add a return into it.

[kaicataldo]

@felixsanz We appreciate the suggestion regardless - thanks for contributing!

[not-an-aardvark]

But don’t you think this is so condensed?

I don’t really see the problem myself, but you could resolve that by adding linebreaks if necessary:

  if (p === 'a') {
    await refactoredFn1()

  } else if (p === 'b') {
    await refactoredFn2()

  } else if (p === 'c') {
    await refactoredFn3()

  } else if (p === 'd') {
    await refactoredFn4()

  } else if (p === 'e') {
    await refactoredFn5()
  }

Even if refactored into functions, using useless return in the last block is useful:

But if you forget to add an explicit return statement in any of the blocks, your code will silently do the wrong thing. Personally, I think having multiple if blocks with return statements in each block is much harder to read than just using if/else directly, because to look at that code, I have to scan through each individual if statement to check if it uses return, and then I have to wonder what happens if none of the conditions match (it seems like nothing happens in your example, but it would be unclear whether this behavior is intentional).