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type StringOrNumber<T extends string | number> = T
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type A = StringOrNumber<string>
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type B = StringOrNumber<number>
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// Type 'boolean' does not satisfy the constraint 'string | number'
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type C = StringOrNumber<boolean>

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type User = {
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  id: number;
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  name: string;
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};
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const getUserName = <T extends User>(arg: T): string => arg.name;
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getUserName({ id: 123, name: 'aaa' });
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getUserName({ id: 123, name: 'aaa', email: 'aaaaaa' });
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11
// Argument of type '{ id: number; }' is not assignable to parameter of type 'User'.
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// Property 'name' is missing in type '{ id: number; }' but required in type 'User'
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getUserName({ id: 123 });

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type User = {
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  id: number;
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  name: string;
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};
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// このコードはどちらも同じ意味
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type UserKey = keyof User; // "id" | "name"
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const id: UserKey = "id"
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const useName: UserKey = "name"
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// Type '"age"' is not assignable to type 'keyof User'.
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const age: UserKey = "age"

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interface Todo {
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  title: string
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  description: string
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  completed: boolean
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}
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type TodoPreview = MyPick<Todo, 'title' | 'completed'>
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const todo: TodoPreview = {
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    title: 'Clean room',
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    completed: false,
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}

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type MyPick<T, K extends keyof T> = {
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  [key in K]: T[key]
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}