Merge pull request #858 from mikinovation/docs/add-no-infer-to-utilit…

…y-type NoInferのドキュメントを追加
yytypescript · May 3, 2024 · aa22efe · aa22efe
2 parents 56bac13 + 93e0896
commit aa22efe
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Showing 6 changed files with 56 additions and 7 deletions.
diff --git a/docs/reference/type-reuse/mapped-types.md b/docs/reference/type-reuse/mapped-types.md
@@ -30,7 +30,7 @@ type Butterfly = {
   [key in SystemSupportLanguage]: string;
 };
 // ---cut---
-// @errors: 2322
+// @errors: 2353
 const butterflies: Butterfly = {
   en: "Butterfly",
   fr: "Papillon",

diff --git a/docs/reference/type-reuse/utility-types/no-infer.md b/docs/reference/type-reuse/utility-types/no-infer.md
@@ -0,0 +1,48 @@
+---
+description: 型推論を防ぐ
+title: NoInfer<T>
+---
+
+`NoInfer<T>`は、`T`の型推論を防ぐためのユーティリティ型です。
+
+## NoInfer&lt;T>の型引数
+
+### T
+
+型引数`T`には推論を防ぎたい型を代入します。
+
+## NoInferの使用例
+
+まずはNoInferを使用しなかった場合の例です。ジェネリクスを使って`getIndexFromArray`という関数を定義します
+
+```ts
+function getIndexFromArray<T extends string>(elements: T[], item: T): number {
+  return elements.findIndex((element) => element === item);
+}
+
+type Fruit = "grape" | "apple" | "banana";
+const fruits: Fruit[] = ["grape", "apple", "banana"];
+getIndexFromArray(fruits, "apple");
+getIndexFromArray(fruits, "peach");
+```
+
+このとき`T`は`"grape" | "apple" | "banana" | "peach"`と推論されてしまいます。しかし第二引数には配列に含まれている要素のみを許容したいです。そこで`NoInfer`を利用することにより`T`の型推論を防ぐことができます。
+
+```ts twoslash
+function getIndexFromArray<T extends string>(
+  elements: T[],
+  item: NoInfer<T>
+): number {
+  return elements.findIndex((element) => element === item);
+}
+
+type Fruit = "grape" | "apple" | "banana";
+const fruits: Fruit[] = ["grape", "apple", "banana"];
+getIndexFromArray(fruits, "apple");
+// @errors: 2345
+getIndexFromArray(fruits, "peach");
+```
+
+## 関連情報
+
+[Infer](../../values-types-variables/type-inference.md)
diff --git a/docs/reference/values-types-variables/object/excess-property-checking.md b/docs/reference/values-types-variables/object/excess-property-checking.md
@@ -9,7 +9,7 @@ TypeScriptのオブジェクトの型には余剰プロパティチェック(exc
 たとえば、`{ x: number }`はプロパティ`x`が必須なオブジェクトの型です。この型に`{ x: 1, y: 2 }`のような値を代入しようとします。この代入は許可されるでしょうか。代入値の型は、必須プロパティの`{ x: number }`を満たしているので問題なさそうです。ところが、この代入は許可されません。
 
 ```ts twoslash
-// @errors: 2322
+// @errors: 2353
 let onlyX: { x: number };
 onlyX = { x: 1 }; // OK
 onlyX = { x: 1, y: 2 }; // コンパイルエラー

diff --git a/package.json b/package.json
@@ -56,7 +56,7 @@
     "react-dom": "^17.0.2",
     "react-nl2br": "^1.0.4",
     "remark-breaks": "^2.0.2",
-    "typescript": "5.2.2",
+    "typescript": "5.4.3",
     "url-loader": "^4.1.1"
   },
   "devDependencies": {

diff --git a/sidebars.js b/sidebars.js
@@ -352,6 +352,7 @@ module.exports = {
                 "reference/type-reuse/utility-types/omit",
                 "reference/type-reuse/utility-types/exclude",
                 "reference/type-reuse/utility-types/extract",
+                "reference/type-reuse/utility-types/no-infer",
               ],
             },
             "reference/type-reuse/mapped-types",

diff --git a/yarn.lock b/yarn.lock
@@ -9896,10 +9896,10 @@ typedarray-to-buffer@^3.1.5:
   dependencies:
     is-typedarray "^1.0.0"
 
-typescript@5.2.2:
-  version "5.2.2"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.2.2.tgz#5ebb5e5a5b75f085f22bc3f8460fba308310fa78"
-  integrity sha512-mI4WrpHsbCIcwT9cF4FZvr80QUeKvsUsUvKDoR+X/7XHQH98xYD8YHZg7ANtz2GtZt/CBq2QJ0thkGJMHfqc1w==
+typescript@5.4.3:
+  version "5.4.3"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.4.3.tgz#5c6fedd4c87bee01cd7a528a30145521f8e0feff"
+  integrity sha512-KrPd3PKaCLr78MalgiwJnA25Nm8HAmdwN3mYUYZgG/wizIo9EainNVQI9/yDavtVFRN2h3k8uf3GLHuhDMgEHg==
 
 typescript@>3:
   version "5.1.6"