sindresorhus/eslint-plugin-unicorn

Rule proposal: `prefer-map-has`

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#1,329 opened on Jun 3, 2021

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help wantednew ruletypes

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Description

When checking existence, should prefer Map#has() over Map#get().

Fail

if (map.get(foo));

Pass

if (map.has(foo));

I think better ship this with prefer-map together, so user can notice this problem when we fix object.foo to map.get(foo) in prefer-map.

Contributor guide

Research direction
Study existing ESLint rule implementations in the plugin (e.g., prefer map) to understand the structure, then create a new rule that detects Map#get() in condition contexts and suggests Map#has().
Tech stack
javascript
Domain
tooling
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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
JavaScriptESLint
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80