Rule-change (`no-return-assign`) - allow assignment in side effect position of comma operator

Update: @platinumazure suggested I filled out the change-rule template:

What rule do you want to change? no-return-assign

Does this change cause the rule to produce more or fewer warnings? Fewer

How will the change be implemented? (New option, new default behavior, etc.)? Change current default behavior (except-parens)

Please provide some example code that this change will affect:

1. return (x = y, x)
2. return ((x = y), x)
3. return (x = y)
4. return x = y
5. return (x, x = y)
6. return (x, (x = y))

What does the rule currently do for this code?

1. Reports error
2. Does not report error
3. Does not report error
4. Reports error
5. Reports error
6. Does not report error

What will the rule do after it’s changed?

Only 1. will change, 1. will no longer report an error because the assignment is in a position of a sequence (comma operator) that is designed for side effects (see MDN example).

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Original issue: no-return-assign - false positive in combination with comma operator

The assignment in the code below is not in ‘return’ position:

[].map(result => (result['x'] = 'y', result))

Example in the online demo

What did you expect to happen?

To have no lint error.

What actually happened? Please include the actual, raw output from ESLint.

It said: Arrow function should not return assignment. (no-return-assign)

[platinumazure]

I’m mildly opposed to changing the rule for this case, but I’m not going to stand in the way if others on the team believe this is a worthwhile change.

Would you mind editing your original post to reflect this rule change proposal template? And in exchange, I’ll relabel this issue as a rule change proposal. Thanks!

[EECOLOR]

@platinumazure I don’t think there is a need to apologize. It might have been my prejudice (coming from other interactions about software) that mistakenly took the “However, this is still a case of an assignment in a return statement (the return statement is implicit due to being a concise arrow body)” as closing the door on the subject.