rules--js-hoist-regexp

rules--js-hoist-regexp is a cursor rule for Cursor from ratnesh-maurya/cursor-claude-personas. It costs 0 tokens per session (294 once invoked), scanned A, original, MIT.

A JavaScript and React pattern for creating regular expressions outside rendering, or reusing them with useMemo. A regular expression is a reusable rule for finding text patterns.

In plain words
What is it for?
Use it in text highlighters, validators, and other React components that repeatedly match text.
Why use it?
Creating the same expression during every render wastes work, while global expressions can also keep changing internal match state.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use it in text highlighters, validators, and other React components that repeatedly match text.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/ratnesh-maurya/cursor-claude-personas

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for rules--js-hoist-regexp

README.md
[![agentmods](https://agentmods.dev/badge/rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp/github.svg)](https://agentmods.dev/rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp)
Your own site
<a href="https://agentmods.dev/rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp"><img src="https://agentmods.dev/badge/rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for rules--js-hoist-regexp

Your own site · 80×15
<a href="https://agentmods.dev/rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp"><img src="https://agentmods.dev/badge/rules/ratnesh-maurya/cursor-claude-personas/rules-js-hoist-regexp.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 294 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.00294
Opus 5 $0.00000 $0.00147
Sonnet 5 $0.00000 $0.00059
Haiku 4.5 $0.00000 $0.00029

Measured 8d ago against content hash f9e9aef2f7c2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

rules--js-hoist-regexp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

3d-frontend-developer/.cursor/rules/rules--js-hoist-regexp.mdc · 46 lines

What it actually says

Hoist RegExp Creation

Don't create RegExp inside render. Hoist to module scope or memoize with useMemo().

Incorrect (new RegExp every render):

function Highlighter({ text, query }: Props) {
  const regex = new RegExp(`(${query})`, 'gi')
  const parts = text.split(regex)
  return <>{parts.map((part, i) => ...)}</>
}

Correct (memoize or hoist):

const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/

function Highlighter({ text, query }: Props) {
  const regex = useMemo(
    () => new RegExp(`(${escapeRegex(query)})`, 'gi'),
    [query]
  )
  const parts = text.split(regex)
  return <>{parts.map((part, i) => ...)}</>
}

Warning (global regex has mutable state):

Global regex (/g) has mutable lastIndex state:

const regex = /foo/g
regex.test('foo')  // true, lastIndex = 3
regex.test('foo')  // false, lastIndex = 0
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 46 lines · 0 tokens per session scan A f9e9aef2f7c2

Subscribe to this mod's changes

rules--js-hoist-regexp is a cursor rule published in the GitHub repository ratnesh-maurya/cursor-claude-personas (8 stars, last pushed 5mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 294 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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