33 JavaScript Concepts is a learning guide that explains core JavaScript ideas through practical examples and selected resources. It helps developers understand topics such as primitive values, objects, coercion, equality, scope, closures, and the call stack. The catalogue add-ons provide skills related to studying or working with the guide.
Borrowing it
Nothing to install: this file belongs to leonardomso/33-js-concepts. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/leonardomso/33-js-concepts/master/.claude/skills/concept-workflow/SKILL.mdgit clone --depth 1 https://github.com/leonardomso/33-js-conceptsWrote 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.
[](https://agentmods.dev/skills/leonardomso/33-js-concepts/concept-workflow)<a href="https://agentmods.dev/skills/leonardomso/33-js-concepts/concept-workflow"><img src="https://agentmods.dev/badge/skills/leonardomso/33-js-concepts/concept-workflow/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.
<a href="https://agentmods.dev/skills/leonardomso/33-js-concepts/concept-workflow"><img src="https://agentmods.dev/badge/skills/leonardomso/33-js-concepts/concept-workflow.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Snyk warn
- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00025 | $0.03721 |
| Opus 5.5 | $0.00010 | $0.01488 |
| Sonnet 5.5 | $0.00005 | $0.00744 |
| Haiku 4.5 | $0.00003 | $0.00372 |
Grade A, and why
concept-workflow 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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 514 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill: Complete Concept Workflow
Use this skill to create a complete, high-quality concept page from start to finish. This skill orchestrates all five specialized skills in the optimal order:
- Resource Curation — Find quality learning resources
- Concept Writing — Write the documentation page
- Test Writing — Create tests for code examples
- Fact Checking — Verify technical accuracy
- SEO Review — Optimize for search visibility
When to Use
- Creating a brand new concept page from scratch
- Completely rewriting an existing concept page
- When you want a full end-to-end workflow with all quality checks
For partial tasks, use individual skills instead:
- Just adding resources? Use
resource-curator - Just writing content? Use
write-concept - Just adding tests? Use
test-writer - Just verifying accuracy? Use
fact-check - Just optimizing SEO? Use
seo-review
Workflow Overview
┌─────────────────────────────────────────────────────────────────────────────┐
│ COMPLETE CONCEPT WORKFLOW │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ INPUT: Concept name (e.g., "hoisting", "event-loop", "promises") │
│ │
│ ┌──────────────────┐ │
│ │ PHASE 1: RESEARCH │ │
│ │ resource-curator │ Find MDN refs, articles, videos │
│ └────────┬─────────┘ │
│ ▼ │
│ ┌──────────────────┐ │
│ │ PHASE 2: WRITE │ │
│ │ write-concept │ Create the documentation page │
│ └────────┬─────────┘ │
│ ▼ │
│ ┌──────────────────┐ │
│ │ PHASE 3: TEST │ │
│ │ test-writer │ Generate tests for all code examples │
│ └────────┬─────────┘ │
│ ▼ │
│ ┌──────────────────┐ │
│ │ PHASE 4: VERIFY │ │
│ │ fact-check │ Verify accuracy, run tests, check links │
│ └────────┬─────────┘ │
│ ▼ │
│ ┌──────────────────┐ │
│ │ PHASE 5: OPTIMIZE│ │
│ │ seo-review │ SEO audit and final optimizations │
│ └────────┬─────────┘ │
│ ▼ │
│ OUTPUT: Complete, tested, verified, SEO-optimized concept page │
│ │
└─────────────────────────────────────────────────────────────────────────────┘
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.
- 2mo ago First seen · 514 lines · 25 tokens per session scan A 933e37f322fa
concept-workflow is a skill published in the GitHub repository leonardomso/33-js-concepts (66,529 stars, last pushed 16d ago), licensed MIT. It adds 25 tokens to every session and 3,721 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-30.
concept-workflow compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| concept-workflowleonardomso/33-js-concepts | Skill | 67k | 16d ago | MIT | A | 25 | Claude Code |
| guided-tourwasp-lang/open-saas | Skill | 16k | 9d ago | MIT | A | 29 | Claude Code |
| image-studio-ui-testsAutomattic/wp-calypso | Skill | 13k | today | GPL-2.0 | A | 52 | Claude Code, Codex |
| typescript-expertpersonamanagmentlayer/pcl | Skill | 44 | 11d ago | Apache-2.0 | A | 40 | Claude Code |
| netsuite-suitescript-learningoracle/netsuite-suitecloud-sdk | Skill | 370 | 7d ago | UPL-1.0 | A | 71 | Claude Code, Codex |
| add-form-managerbishopZ/2026-Boilerplate | Skill | 24 | 3mo ago | MIT | A | 22 | Claude Code, Codex |
| migrate-api-to-tanstack-querybishopZ/2026-Boilerplate | Skill | 24 | 3mo ago | MIT | A | 32 | Claude Code, Codex |