modern-javascript-patterns

modern-javascript-patterns is a skill for Claude Code, Codex from hybridlabor-api/bdb-dev-optimized-agent-skills. It costs 38 tokens per session (329 once invoked), scanned A, original, Apache-2.0.

A guide to modern JavaScript features and programming patterns for writing clearer, more maintainable code.

In plain words
What is it for?
Use it when refactoring legacy JavaScript, using promises and async functions, improving performance, or building web applications.
Why use it?
It helps replace outdated or hard-to-follow code with simpler approaches and avoid common problems with asynchronous work and data transformations.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

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.

agentmods
npx agentmods add skills/hybridlabor-api/bdb-dev-optimized-agent-skills/modern-javascript-patterns
Any agent
npx skills add hybridlabor-api/bdb-dev-optimized-agent-skills --skill modern-javascript-patterns
Clone the repo
git clone --depth 1 https://github.com/hybridlabor-api/bdb-dev-optimized-agent-skills

Made for: Claude Code, Codex.

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 modern-javascript-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/modern-javascript-patterns.svg)](https://agentmods.dev/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/modern-javascript-patterns)
Your own site
<a href="https://agentmods.dev/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/modern-javascript-patterns"><img src="https://agentmods.dev/badge/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/modern-javascript-patterns.svg" alt="Measured on agentmods" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 329 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00038 $0.00329
Opus 5 $0.00019 $0.00164
Sonnet 5 $0.00008 $0.00066
Haiku 4.5 $0.00004 $0.00033

Measured 2d ago against content hash 51e510010e68, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

modern-javascript-patterns 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 2d 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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

skills/global_config/modern-javascript-patterns/SKILL.md · 45 lines

What it actually says

Modern JavaScript Patterns

Comprehensive guide for mastering modern JavaScript (ES6+) features, functional programming patterns, and best practices for writing clean, maintainable, and performant code.

Use this skill when

  • Refactoring legacy JavaScript to modern syntax
  • Implementing functional programming patterns
  • Optimizing JavaScript performance
  • Writing maintainable and readable code
  • Working with asynchronous operations
  • Building modern web applications
  • Migrating from callbacks to Promises/async-await
  • Implementing data transformation pipelines

Do not use this skill when

  • The task is unrelated to modern javascript patterns
  • You need a different domain or tool outside this scope

Instructions

  • Clarify goals, constraints, and required inputs.
  • Apply relevant best practices and validate outcomes.
  • Provide actionable steps and verification.
  • If detailed examples are required, open resources/implementation-playbook.md.

Resources

  • resources/implementation-playbook.md for detailed patterns and examples.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 45 lines · 38 tokens per session scan A 51e510010e68

Subscribe to this mod's changes

modern-javascript-patterns is a skill published in the GitHub repository hybridlabor-api/bdb-dev-optimized-agent-skills (6 stars, last pushed yesterday), licensed Apache-2.0. It adds 38 tokens to every session and 329 once invoked, about $0.0002 per session on Opus 5. 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.