non-null-assertion SKILL.md skillA
non-null-assertion from ncaq/konoka is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add ncaq/konoka/non-null-assertion@git:20260407.8cdba48Pins git:20260407.8cdba48 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- ncaq/konoka
- Path
plugins/web-tasuke/skills/non-null-assertion/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260407.8cdba48, committed Apr 7, 2026
- Size
- 2,281 bytes
- Repository stars
- 3
- License
- Apache-2.0
Do not use non-null assertion operator (!) in TypeScript. Use optional chaining, type guards, or nullish checks instead. Use when writing or reviewing TypeScript code.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Non-null Assertion (`!`)の禁止
Non-null assertion演算子(`!`)はTypeScriptの型安全性を破壊するため、使用しないでください。
`!`を付けた時点でコンパイラによるnullチェックが無効化され、実行時エラーの原因になります。
ESLintでも`@typescript-eslint/no-non-null-assertion`ルールとしてよく禁止されています。
## 代替手段
### Optional chaining
値がnullableかもしれない場合は`?.`で安全にアクセスしてください。
```typescript
// Bad
const name = users[0]!.name;
// Good
const name = users[0]?.name;
const name = users.at(0)?.name;
```
### Type guardによる絞り込み
Map等からの取得など、型が`T | undefined`になる場面ではnullチェックで絞り込んでください。
```typescript
// Bad
const config = configMap.get(key)!;
applyConfig(config);
// Good
const config = configMap.get(key);
if (config == null) {
throw new Error(`Config not found for key: ${key}`);
}
applyConfig(config);
```
### `filter`の使用
`filter`はtype guardとして機能するため、
nullableな要素の除去に活用できます。
明示的なtype predicateの記述は不要です。
```typescript
// Bad: non-null assertionで無理やり絞り込む
const names = users.map((u) => u.name!);
// Good: filterで型安全にundefinedを除去(TypeScript 5.5以降)
const names = users.map((u) => u.name).filter((name) => name != null);
// names: string[]
```
### テストコードでの扱い
jestやvitestで`expect(value).toBeDefined()`を書いてもTypeScript上はnullableのままです。
Node.jsやvitestの`assert`を使ってください。
```typescript
…Read the whole file at its exact version.
How to install
mdr add ncaq/konoka/non-null-assertion@sha256:9c73cbbbce7da97cThe line at the top of this page pins the label git:20260407.8cdba48, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_onxzk6gbauddegev)
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Versions
The registry has recorded 1 version of this file, committed on Apr 7, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (2281 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
ncaq/konoka · 3 stars · license Apache-2.0 · pushed 2026-10-19 · branch master
API
GET https://markdownregistry.com/api/v1/artifacts/art_onxzk6gbauddegev GET https://markdownregistry.com/api/v1/resolve?ref=ncaq/konoka/non-null-assertion GET https://markdownregistry.com/api/v1/blob/9c73cbbbce7da97c0b9ed8be66a9fe03b08e92458b5d6191fda770ad84a646d7
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.