update docs

src/docs/typescript/utility-types.md

@@ -1,8 +1,8 @@
 ---
-title: TypeScript 内置工具类型
+title: TypeScript 内置工具类型的源码实现
 ---
 
-# TypeScript 内置工具类型
+# TypeScript 内置工具类型的源码实现
 
 ## Awaited\<Type>
 
@@ -56,10 +56,10 @@ interface Todo {
 type PartialTodo = Partial<Todo>
 
 // 等价于
-// type PartialTodo = {
-//  title?: string
-//  description?: string
-// }
+type PartialTodo = {
+ title?: string
+ description?: string
+}
 ```
 
 源码实现：
@@ -80,13 +80,13 @@ interface Props {
   b?: string
 }
 
-type RequiredProps = Required<Props> 
+type RequiredProps = Required<Props>
 
 // 等价于
-// type RequiredProps = {
-//   a: number
-//   b: string
-// }
+type RequiredProps = {
+  a: number
+  b: string
+}
 ```
 
 源码实现：
@@ -110,9 +110,9 @@ interface Todo {
 type ReadonlyTodo = Readonly<Todo>
 
 // 等价于
-// type ReadonlyTodo = {
-//   readonly title: string
-// }
+type ReadonlyTodo = {
+  readonly title: string
+}
 ```
 
 源码实现：
@@ -150,6 +150,144 @@ type Record<K extends keyof any, T> = {
 }
 ```
 
+## Pick<Type, Keys>
+
+从 Type 中选取属性 Keys（字符串字面量或字符串字面量的组合）集，构建一个类型。
+
+```ts
+interface Todo {
+  title: string
+  description: string
+  completed: boolean
+}
+
+type TodoPreview = Pick<Todo, "title" | "completed">
+
+// 等价于
+interface TodoPreview {
+  title: string
+  completed: boolean
+}
+```
+
+源码实现：
+
+```ts
+type Pick<T, K extends keyof T> = {
+  [P in K]: T[P]
+}
+```
+
+## Omit<Type, Keys>
+
+从 Type 中选取所有属性，然后删除键（字符串字面量或字符串字面量的联合），从而构造一个类型。与 Pick 相反。
+
+```ts
+
+interface Todo {
+  title: string
+  description: string
+  completed: boolean
+  createdAt: number
+}
+
+type TodoPreview = Omit<Todo, "description">
+
+// 等价于
+interface TodoPreview {
+  title: string
+  completed: boolean
+  createdAt: number
+}
+```
+
+源码实现：
+
+```ts
+type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>
+```
+
+## Exclude<UnionType, ExcludedMembers>
+
+通过从 UnionType 中排除所有可赋值给 ExcludedMembers 的联合成员来构造一个类型。
+
+```ts
+type T0 = Exclude<"a" | "b" | "c", "a">
+// type T0 = "b" | "c"
+
+type T1 = Exclude<"a" | "b" | "c", "a" | "b">
+// type T1 = "c"
+
+type T2 = Exclude<string | number | (() => void), Function>
+// type T2 = string | number
+
+type Shape =
+  | { kind: "circle"; radius: number }
+  | { kind: "square"; x: number }
+  | { kind: "triangle"; x: number; y: number }
+type T3 = Exclude<Shape, { kind: "circle" }>
+// type T3 = {
+//   kind: "square"
+//   x: number
+// } | {
+//   kind: "triangle"
+//   x: number
+//   y: number
+// }
+```
+
+源码实现：
+
+```ts
+type Exclude<T, U> = T extends U ? never : T
+```
+
+## Extract<Type, Union>
+
+从 Type 中提取可赋值给 Union 的所有 union 成员，从而构造一个类型。
+
+```ts
+type T0 = Extract<"a" | "b" | "c", "a" | "f">
+// type T0 = "a"
+
+type T1 = Extract<string | number | (() => void), Function>
+// type T1 = () => void
+
+type Shape =
+  | { kind: "circle"; radius: number }
+  | { kind: "square"; x: number }
+  | { kind: "triangle"; x: number; y: number }
+type T2 = Extract<Shape, { kind: "circle" }>
+// type T2 = {
+//   kind: "circle";
+//   radius: number;
+// }
+```
+
+源码实现：
+
+```ts
+type Extract<T, U> = T extends U ? T : never
+```
+
+## NonNullable\<Type>
+
+通过从 Type 中排除 null 和 undefined 来构造一个类型。
+
+```ts
+type T0 = NonNullable<string | number | undefined>
+// type T0 = string | number
+
+type T1 = NonNullable<string[] | null | undefined>
+// type T1 = string[]
+```
+
+源码实现：
+
+```ts
+type NonNullable<T> = T extends null | undefined ? never : T
+```
+
 ## 参考
 
 https://www.typescriptlang.org/docs/handbook/utility-types.html