sindresorhus/eslint-plugin-unicorn

Rule proposal: `prefer-string-repeat`

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#1,708 opened on Jan 28, 2022

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help wantednew rule

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Description

Description

There are legacy ways to repeat string, we should replace them with .repeat(), but this proposal is not about that. I want enforce .repeat() for unreadable repeating string literals.

Fail

const string = '    '; // I can't see how many are there


const string = 'unicorn unicorn unicorn unicorn';

Pass

const string = ' '.repeat(4);

const string = 'unicorn '.repeat(4).trim();  // This?
const string = Array.from({length: 4}).fill('unicorn').join(' '); // Or this?
const string = Array.from({length: 4}, () => 'unicorn').join(' '); // Or this?

Contributor guide

Research direction
Implement an ESLint rule that detects string literals containing repeated substrings (e.g., ' ' or 'unicorn unicorn') and suggests using .repeat(). Use AST visitor to find Literal nodes, then check if the string value consists of a repeating pattern. Include an auto fix option that replaces the literal with the .repeat() expression.
Tech stack
javascript
Domain
developer 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.
1-2 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
ESLintJavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60