sindresorhus/eslint-plugin-unicorn

`explicit-length-check`: ignore variables with non-array properties?

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#1,266 opened on May 12, 2021

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Description

if (
  dimensions.width &&
  dimensions.height &&
  dimensions.length // violation reported by unicorn/explicit-length-check
) { }

In this example, packagingData.dimensions is an object, and length could be a string.

As a heuristic to avoid false positives with detecting length or size on variables that are not actually arrays, could we ignore variables that have non-array properties? For example, an array does not have a width property, so if we see that used, we would assume dimensions is not an array, and ignore it.

Contributor guide

Research direction
Investigate the current implementation of the `explicit length check` rule in `rules/explicit length check.js`. Understand how it detects violations and consider adding logic to check if the variable has other property accesses that are not typical for arrays (e.g., `.width`, `.height`). Review any existing tests to ensure the heuristic does not introduce false negatives. The issue suggests using a heuristic: if a variable has non array properties, ignore it. Implement this and add appropriate tests.
Tech stack
javascriptnodejs
Domain
tooling
Issue type
Feature
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.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
JavaScriptESLint rule APIAST basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45