# JavaScript Language Patterns

> Modern JavaScript (ES2022+) patterns for clean, maintainable code.

- **Type:** Skill
- **Install:** `agentstack add skill-hoangnguyen0403-agent-skills-standard-language`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [HoangNguyen0403](https://agentstack.voostack.com/s/hoangnguyen0403)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [HoangNguyen0403](https://github.com/HoangNguyen0403)
- **Source:** https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/.agents/skills/javascript/language
- **Website:** https://www.npmjs.com/package/agent-skills-standard

## Install

```sh
agentstack add skill-hoangnguyen0403-agent-skills-standard-language
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# JavaScript Language Patterns

## **Priority: P0 (CRITICAL)**

Modern JavaScript standards for clean, maintainable code.

## Implementation Guidelines

- **Variables**: `const` default. `let` if needed. No `var`.
- **Functions**: Arrows for callbacks. Declarations for top-level.
- **Async**: `async/await` + `try/catch`.
- **Objects**: Destructuring, Spread `...`, Optional Chain `?.`, Nullish `??`.
- **Strings**: Template literals `${}`.
- **Arrays**: `map`, `filter`, `reduce`. No loops.
- **Modules**: ESM `import`/`export`. Export only what is necessary.
- **Classes**: Use `#private` fields for true privacy.

## Anti-Patterns

- **No `var`**: Block scope only.
- **No `==`**: Strict `===`.
- **No `new Object()`**: Use literals `{}`.
- **No Callbacks**: Promisify everything.
- **No Mutation**: Immutability first.

## Code

```javascript
// Modern Syntax
const [x, ...rest] = items;
const name = user?.profile?.name ?? 'Guest';

// Async
async function getUser(id) {
  try {
    const res = await fetch(`/api/${id}`);
    return res.json();
  } catch (err) {
    console.error(err);
    throw err;
  }
}

// Class + Private
class Service {
  #key;
  constructor(k) {
    this.#key = k;
  }
}
```

## Reference & Examples

For advanced patterns and functional programming:
See [references/REFERENCE.md](references/REFERENCE.md).

## Related Topics

best-practices | tooling

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [HoangNguyen0403](https://github.com/HoangNguyen0403)
- **Source:** [HoangNguyen0403/agent-skills-standard](https://github.com/HoangNguyen0403/agent-skills-standard)
- **License:** Apache-2.0
- **Homepage:** https://www.npmjs.com/package/agent-skills-standard

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-hoangnguyen0403-agent-skills-standard-language
- Seller: https://agentstack.voostack.com/s/hoangnguyen0403
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.