Enforce `.replaceAll()` over `.split().join()` in `prefer-string-replace-all` rule

Description

foo.split('a').join('b');

foo.replaceAll('a', 'b');

// Not sure about this, maybe add `g` flag, result the same?
foo.split(/a+/).join('b');

// Different with foo.replaceAll('', 'b');
foo.split('').join('b');

Contributor guide

Tech stack

javascriptnodejs

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.

fresh

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

familiarity with ESLint rulesAST manipulationJavaScript

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

40

Research direction

Examine the existing rule implementation in the eslint plugin unicorn repository, specifically the `prefer string replace all` rule file (`rules/prefer string replace all.js`). Understand how the rule currently detects `.replaceAll()` usage and how to add detection for `.split().join()` patterns. Review the test file for that rule to see existing test cases. Consider edge cases like using regex or empty string in split. The issue author suggested that `.split(/a+/).join('b')` might be equivalent, while `.split('').join('b')` is different. Investigate these and implement the check.