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Agent skill

Typescript Strict Mode

by thedaviddias in thedaviddias/Front-End-Checklist

A skill your agent uses when setting up a new TypeScript project, auditing an existing tsconfig.json, or reviewing code where null-reference errors or implicit any types are present.

MITAuto-check passed

Install Typescript Strict Mode

skills CLI
$ npx skills add thedaviddias/Front-End-Checklist --skill typescript-strict-mode -a claude-code

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

GitHub CLI
$ gh skill install thedaviddias/Front-End-Checklist typescript-strict-mode --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/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/typescript-strict-mode .claude/skills/typescript-strict-mode && 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
typescript-strict-mode
GitHub stars
74k
Token cost
~526 tokens
SKILL.md length
221 words
Files
2 (incl. references)
Skills in repo
390
Repo updated
First seen
Licence
MIT

At a glance

A skill your agent uses when setting up a new TypeScript project, auditing an existing tsconfig.json, or reviewing code where null-reference errors or implicit any types are present.

  • Setting up a new TypeScript project
  • SKILL.md covers Quick Reference, Check, Fix and Explain, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Auditing an existing tsconfig.json

What it does

Typescript Strict Mode is an agent skill from thedaviddias/Front-End-Checklist. Use when setting up a new TypeScript project, auditing an existing tsconfig.json, or reviewing code where null-reference errors or implicit any types are present.

Its SKILL.md is about 530 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/rule.md`).

It works with TypeScript. The repository describes itself as: 🗂 The essential checklist for modern web development, for humans and AI agents. The licence is MIT.

When your agent uses it

  • Setting up a new TypeScript project
  • Auditing an existing tsconfig.json
  • Reviewing code where null-reference errors
  • Implicit any types are present

Example prompts

  • “/typescript-strict-mode”

What it can do on your machine

Read from SKILL.md and the folder at commit e8d14d0. 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

    Links to these hosts (documentation or services it may open):

    • frontendchecklist.io

    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

Typescript Strict Mode loads about 526 tokens when it runs, and up to ~2.5k if it reads all its reference files. Until then it costs about 46 tokens; SKILL.md has 221 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~46
When it runs · the whole SKILL.md, loaded when a task matches
~526
With references · SKILL.md plus every file in references/, read only if the agent opens them
~2.5k

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 thedaviddias/Front-End-Checklist at commit e8d14d0, republished under its MIT licence (© thedaviddias). 221 words, ~526 tokens.

Download SKILL.mdSave it as .claude/skills/typescript-strict-mode/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
typescript-strict-mode
description
Use when setting up a new TypeScript project, auditing an existing tsconfig.json, or reviewing code where null-reference errors or implicit any types are present.
metadata.category
javascript
metadata.priority
high
metadata.difficulty
beginner
metadata.estimatedTime
15
metadata.source
frontendchecklist.io
metadata.url
https://frontendchecklist.io/rules/javascript/typescript-strict-mode

Enable TypeScript strict mode in tsconfig.json

Without strict mode, TypeScript allows implicit any types, ignores possible null/undefined values, and silently accepts unsound function assignments — meaning the type system gives a false sense of safety. Enabling strict mode makes TypeScript catch the bugs it was designed to prevent, turning type errors into compile-time failures rather than runtime surprises in production.

Quick Reference

  • "strict": true enables strictNullChecks, noImplicitAny, and six other checks
  • Enable strict from project start — retrofitting a large codebase is painful
  • On existing projects: enable strictNullChecks first, then other flags incrementally
  • Strict mode eliminates entire classes of null reference and implicit-any bugs

Check

Inspect the tsconfig.json in this project and report whether "strict": true (or individual strict flags) is enabled. List any missing strict flags.

Fix

Add "strict": true to the compilerOptions in tsconfig.json. If the project has existing type errors, explain how to enable strictNullChecks first as a stepping stone.

Explain

Explain what TypeScript strict mode enables, which individual flags it activates, and why each flag matters for catching real bugs.

Code Review

Check whether the codebase relies on implicit any, unchecked null access, or loose function type assignments that strict mode would reject. Flag the specific patterns and show what stricter types would look like.

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/javascript/typescript-strict-mode

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

Files

SKILL.md and 1 other file (references) in skills/typescript-strict-mode of thedaviddias/Front-End-Checklist.

  • SKILL.md
  • references/rule.md

Open the folder on GitHubat commit e8d14d0

Compare with similar skills

Typescript Strict Mode 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.

Typescript Strict Mode compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Typescript Strict Mode this skillthedaviddias/Front-End-Checklist74k—~526Automated safety check: PassMIT
MCP Server Builderanthropics/skills180k63 repos~2.3kAutomated safety check: PassApache-2.0
Web Artifacts Builderanthropics/skills180k41 repos~769Automated safety check: PassApache-2.0
Typescript Advanced Typesrolling-scopes/rsschool-app10k25 repos~4.2kAutomated safety check: PassMPL-2.0
Code Review ChecklistshareAI-lab/learn-claude-code78k5 repos~1.1kAutomated safety check: PassMIT
MCP Server BuildershareAI-lab/learn-claude-code78k5 repos~1.2kAutomated safety check: PassMIT

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Works with

Questions about Typescript Strict Mode

What does Typescript Strict Mode do?

A skill your agent uses when setting up a new TypeScript project, auditing an existing tsconfig.json, or reviewing code where null-reference errors or implicit any types are present. Typescript Strict Mode is an agent skill from thedaviddias/Front-End-Checklist.json, or reviewing code where null-reference errors or implicit any types are present.

When should I use Typescript Strict Mode?

Typescript Strict Mode fits situations like: setting up a new TypeScript project; auditing an existing tsconfig.json; reviewing code where null-reference errors; implicit any types are present.

How do I install Typescript Strict Mode in Claude Code?

Run `npx skills add thedaviddias/Front-End-Checklist --skill typescript-strict-mode -a claude-code`. Or copy the skill folder (skills/typescript-strict-mode in thedaviddias/Front-End-Checklist) into .claude/skills/typescript-strict-mode in your project. Claude Code loads it when a task matches its description.

How do I install Typescript Strict Mode in Codex?

Run `npx skills add thedaviddias/Front-End-Checklist --skill typescript-strict-mode -a codex`. Or copy the skill folder (skills/typescript-strict-mode in thedaviddias/Front-End-Checklist) into .agents/skills/typescript-strict-mode in your project. Codex loads it when a task matches its description.

Can I use Typescript Strict Mode 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 thedaviddias/Front-End-Checklist --skill typescript-strict-mode -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/typescript-strict-mode, .gemini/skills/typescript-strict-mode, .github/skills/typescript-strict-mode and .opencode/skills/typescript-strict-mode in your project.

What does Typescript Strict Mode need to run?

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

Does Typescript Strict Mode access the network?

SKILL.md names 1 domain. As links in the text: frontendchecklist.io. This is read from the text; nothing was executed.

Is Typescript Strict Mode 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 Typescript Strict Mode use?

Typescript Strict Mode 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 Typescript Strict Mode use?

About 526 tokens (SKILL.md is roughly 2.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 2k tokens, read only when the agent opens those files.

What are the alternatives to Typescript Strict Mode?

Skills that share tags, products or a category with Typescript Strict Mode: MCP Server Builder (anthropics/skills, 180k stars), Web Artifacts Builder (anthropics/skills, 180k stars), Typescript Advanced Types (rolling-scopes/rsschool-app, 10k stars) and Code Review Checklist (shareAI-lab/learn-claude-code, 78k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Typescript Strict Mode?

thedaviddias (a GitHub user) maintains it in thedaviddias/Front-End-Checklist, which has 74,412 GitHub stars. The repository holds 390 skills in this directory. The repository was last updated on October 6, 2026.

Source: thedaviddias/Front-End-Checklist on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.