sindresorhus/eslint-plugin-unicorn

`prefer-array-some`: Trigger through variable assignment

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#996 opened on Jan 5, 2021

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enhancementhelp wanted

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Description

The prefer-array-some rule is not triggered when the .find() result is assigned to a variable:

const arr = [];
const hasFoo = arr.find(val => val === 'foo');
if (hasFoo) console.log('foo');

Obviously it shouldn't be triggered if hasFoo were to be used elsewhere for anything other than element existence checks, but if that's all it's used for, I'd expect it to trigger the rule.

Variable assignment of these element existence checks is useful when the predicate function is long, but also to generally make code read more prose-like.

Contributor guide

Research direction
Review the rule implementation in `rules/prefer array some.js` to understand current AST checks. The issue requests triggering when `.find()` result is assigned to a variable and only used for boolean checks. Look at existing tests in `test/snapshots/` for this rule to see covered cases. Consider commenting in the issue to confirm approach with maintainers.
Tech stack
javascript
Domain
toolingdeveloper experience
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.
Clear
Prerequisites
ESLint plugin basicsAST understanding
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60