sindresorhus/eslint-plugin-unicorn

Rule proposal: Prefer `String#matchAll()`

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#574 opened on Mar 3, 2020

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 (6 comments) (5 reactions) (0 assignees)JavaScript (5,022 stars) (468 forks)user submission
help wantednew rule

Description

Not offering a PR here, but just thought such a rule could possibly fit your project...

Namely, preferring String.prototype.matchAll to while loop exec assignments.

As per https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/matchAll#Examples , one can replace this:

let match;
while ((match = regexp.exec(str)) !== null) {
}

..with the likes of:

for (const match of str.matchAll(regexp)) {
}

I find it quite a bit more elegant and semantic, and it allows avoiding defining a variable in the parent block.

If not, no worries, just thought I'd see if it might pique the interest of others.

Contributor guide

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.
3-5 days
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
Understanding of ESLint plugin developmentFamiliarity with regular expressions
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Review the existing rules in eslint plugin unicorn to understand the pattern for adding a new rule. Look at examples like the 'prefer string slice' rule for code structure. Check the maintainer's comments for any additional requirements or preferences. Implement the rule to detect `while (match = regexp.exec(str))` and suggest `String.prototype.matchAll` with a for of loop.