nullish-undefined-null SKILL.md skillA
nullish-undefined-null 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/nullish-undefined-null@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/nullish-undefined-null/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260407.8cdba48, committed Apr 7, 2026
- Size
- 2,417 bytes
- Repository stars
- 3
- License
- Apache-2.0
Prefer undefined over null in TypeScript/JavaScript. Use == null for nullish checks. Use when writing or reviewing code that handles absent values.
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
# `null`より`undefined`を優先して使う
TypeScript/JavaScriptにおいて`undefined`と`null`が両方あるのは単なる歴史的経緯による混乱なので、
なるべく`undefined`だけを使うようにしてください。
## nullを使って良い場合
### 特別なnull
既存のAPIで`null`に意味がある場合は許容されます。
例えばReactのコンポーネントが返却する`null`は何も描画しないことを表します。
そのように様々な既存のライブラリで、
`null`が自然に発生する箇所では`null`のまま扱っても構いません。
`undefined`に変換するのは必須ではありません。
「選択の余地がある場合に`undefined`を優先する」というポリシーであり、
`null`を逐一排除するものではありません。
## nullishとの比較には `== null` / `!= null` を使う
Nullish valueである`undefined`や`null`との比較には、
基本的には、
厳密等価演算子(`=== undefined`, `!== undefined`, `=== null`, `!== null`)ではなく、
抽象等価演算子 (`== null`, `!= null`) を使ってください。
`== null`は`undefined`と`null`の両方にマッチするため、
どちらか一方のチェック漏れを防げます。
これらを厳密に分ける必要はほぼないはずです。
厳密に分けているインターフェイスはあまり良くないのですが、
既存のインターフェイスがそうであれば仕方がありません。
ESLintの`eqeqeq`ルールが`always`に設定されていると`== null`が警告されますが、
現代の一般的なESLint設定では`smart`オプションが有効になっており、
`null`との比較に`==`/`!=`を使うケースは許容されるため基本的に問題ありません。
```typescript
// 良い例
if (value == null) {
/* value is null or undefined */
}
if (value != null) {
/* value is neither null nor undefined */
}
// 避ける例
if (value === null || value === undefined) {
/* 冗長 */
}
if (value !== null && value !== undefined) {
/* 冗長 */
}
if (value === null) {
…Read the whole file at its exact version.
How to install
mdr add ncaq/konoka/nullish-undefined-null@sha256:03310694a7c172a5The 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_cpwieckzhyvcafdr)
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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 (2417 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_cpwieckzhyvcafdr GET https://markdownregistry.com/api/v1/resolve?ref=ncaq/konoka/nullish-undefined-null GET https://markdownregistry.com/api/v1/blob/03310694a7c172a560797b0de9ec92d6eb408da257ad6f53400b1bfb995c1dc3
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.