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Official agent skill

Javascript Typescript Jest

by github in github/awesome-copilot

Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns.

OfficialMITAuto-check passedTesting & QA

Install Javascript Typescript Jest

skills CLI
$ npx skills add github/awesome-copilot --skill javascript-typescript-jest -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install github/awesome-copilot javascript-typescript-jest --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/github/awesome-copilot.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/javascript-typescript-jest .claude/skills/javascript-typescript-jest && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
javascript-typescript-jest
GitHub stars
40k
Used in
1 other repo
Token cost
~559 tokens
SKILL.md length
203 words
Files
1
Skills in repo
417
Repo updated
First seen
Licence
MIT

At a glance

Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns.

  • Tasks that involve Unit testing
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Javascript Typescript Jest is an agent skill from github/awesome-copilot, published by the product's own GitHub organization. Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns.

Its SKILL.md is about 560 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA, covering Unit testing. It works with Jest, JavaScript and TypeScript. The repository describes itself as: Community-contributed instructions, agents, skills, and configurations to help you make the most of GitHub Copilot. The licence is MIT.

When your agent uses it

  • Tasks that involve Unit testing

Example prompts

  • “/javascript-typescript-jest”

What it can do on your machine

Read from SKILL.md and the folder at commit 7cce7cf. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Javascript Typescript Jest loads about 559 tokens when it runs. Until then it costs about 40 tokens; SKILL.md has 203 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~40
When it runs · the whole SKILL.md, loaded when a task matches
~559

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from github/awesome-copilot at commit 7cce7cf, republished under its MIT licence (© github). 203 words, ~559 tokens.

Download SKILL.mdSave it as .claude/skills/javascript-typescript-jest/SKILL.md (or your agent's skills folder).
name
javascript-typescript-jest
description
Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns.
Test Structure
  • Name test files with .test.ts or .test.js suffix
  • Place test files next to the code they test or in a dedicated __tests__ directory
  • Use descriptive test names that explain the expected behavior
  • Use nested describe blocks to organize related tests
  • Follow the pattern: describe('Component/Function/Class', () => { it('should do something', () => {}) })
Effective Mocking
  • Mock external dependencies (APIs, databases, etc.) to isolate your tests
  • Use jest.mock() for module-level mocks
  • Use jest.spyOn() for specific function mocks
  • Use mockImplementation() or mockReturnValue() to define mock behavior
  • Reset mocks between tests with jest.resetAllMocks() in afterEach
Testing Async Code
  • Always return promises or use async/await syntax in tests
  • Use resolves/rejects matchers for promises
  • Set appropriate timeouts for slow tests with jest.setTimeout()
Snapshot Testing
  • Use snapshot tests for UI components or complex objects that change infrequently
  • Keep snapshots small and focused
  • Review snapshot changes carefully before committing
Testing React Components
  • Use React Testing Library over Enzyme for testing components
  • Test user behavior and component accessibility
  • Query elements by accessibility roles, labels, or text content
  • Use userEvent over fireEvent for more realistic user interactions

Common Jest Matchers

  • Basic: expect(value).toBe(expected), expect(value).toEqual(expected)
  • Truthiness: expect(value).toBeTruthy(), expect(value).toBeFalsy()
  • Numbers: expect(value).toBeGreaterThan(3), expect(value).toBeLessThanOrEqual(3)
  • Strings: expect(value).toMatch(/pattern/), expect(value).toContain('substring')
  • Arrays: expect(array).toContain(item), expect(array).toHaveLength(3)
  • Objects: expect(object).toHaveProperty('key', value)
  • Exceptions: expect(fn).toThrow(), expect(fn).toThrow(Error)
  • Mock functions: expect(mockFn).toHaveBeenCalled(), expect(mockFn).toHaveBeenCalledWith(arg1, arg2)

© github, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/javascript-typescript-jest of github/awesome-copilot.

Open the folder on GitHubat commit 7cce7cf

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in github/awesome-copilot, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Javascript Typescript Jest next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Javascript Typescript Jest compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Javascript Typescript Jest this skillgithub/awesome-copilot40k1 repos~559Automated safety check: PassMIT
Jest Skillsickn33/agentic-awesome-skills47k1 repos~1.4kAutomated safety check: PassMIT
Vitest Skillsickn33/agentic-awesome-skills47k1 repos~1.2kAutomated safety check: PassMIT
Jest UnitPramodDutta/qaskills232—~3.8kAutomated safety check: PassMIT
Experience Lwc Typescript Migrateforcedotcom/sf-skills1.1k—~2.1kAutomated safety check: PassApache-2.0
Typescript Rulessoftspark/ai-toolkit179—~2.7kAutomated safety check: NotesApache-2.0

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Works with

Categories

Questions about Javascript Typescript Jest

What does Javascript Typescript Jest do?

Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns. Javascript Typescript Jest is an agent skill from github/awesome-copilot, published by the product's own GitHub organization. Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns.

When should I use Javascript Typescript Jest?

Javascript Typescript Jest fits situations like: tasks that involve Unit testing.

How do I install Javascript Typescript Jest in Claude Code?

Run `npx skills add github/awesome-copilot --skill javascript-typescript-jest -a claude-code`. Or copy the skill folder (skills/javascript-typescript-jest in github/awesome-copilot) into .claude/skills/javascript-typescript-jest in your project. Claude Code loads it when a task matches its description.

How do I install Javascript Typescript Jest in Codex?

Run `npx skills add github/awesome-copilot --skill javascript-typescript-jest -a codex`. Or copy the skill folder (skills/javascript-typescript-jest in github/awesome-copilot) into .agents/skills/javascript-typescript-jest in your project. Codex loads it when a task matches its description.

Can I use Javascript Typescript Jest in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add github/awesome-copilot --skill javascript-typescript-jest -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/javascript-typescript-jest, .gemini/skills/javascript-typescript-jest, .github/skills/javascript-typescript-jest and .opencode/skills/javascript-typescript-jest in your project.

What does Javascript Typescript Jest need to run?

SKILL.md names no scripts, command-line tools or credentials: Javascript Typescript Jest is instructions for the agent only.

Does Javascript Typescript Jest access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Javascript Typescript Jest safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Javascript Typescript Jest use?

Javascript Typescript Jest is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Javascript Typescript Jest use?

About 559 tokens (SKILL.md is roughly 2.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Javascript Typescript Jest?

Skills that share tags, products or a category with Javascript Typescript Jest: Jest Skill (sickn33/agentic-awesome-skills, 47k stars), Vitest Skill (sickn33/agentic-awesome-skills, 47k stars), Jest Unit (PramodDutta/qaskills, 232 stars) and Experience Lwc Typescript Migrate (forcedotcom/sf-skills, 1.1k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Javascript Typescript Jest?

github (a GitHub organization, an official publisher) maintains it in github/awesome-copilot, which has 39,792 GitHub stars. The repository holds 417 skills in this directory. The repository was last updated on October 8, 2026.

Source: github/awesome-copilot on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.