sindresorhus/eslint-plugin-unicorn

`no-fn-reference-in-iterator` false positives on non-array methods

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#568 opened on Feb 27, 2020

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Description

const obj = {filter: () => {}};
obj.filter([].join()); // error: Do not pass a function reference directly to an iterator method

.filter is not an iterator here. I think the rule confuses it with Array.prototype.filter and the false-positive seems specifically triggered by a CallExpression argument.

The autofix produces broken code for this case.

Contributor guide

Research direction
Investigate the rule implementation in `rules/no fn reference in iterator.js`. The bug is that the rule incorrectly flags non array methods like `obj.filter`. The fix should ensure the rule only applies to array method calls, possibly by checking the type of the object or using a list of known array methods. Review the comments on the issue for any proposed solutions.
Tech stack
javascript
Domain
toolingdeveloper experience
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
basic JavaScriptESLint rule development
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40