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Commit d2c7e92

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added multiple helper typescript types
1 parent 27d8016 commit d2c7e92

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10 files changed

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---
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title: At Least One Key
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description: Ensures that at least one property of an object is required.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition
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---
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```ts
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type AtLeastOne<T> = {
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[K in keyof T]: Pick<T, K> & Partial<Omit<T, K>>;
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}[keyof T];
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// Usage:
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type A = {
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id?: string;
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name?: string;
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isActive?: boolean;
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};
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type AtLeastOneA = AtLeastOne<A>;
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// Requires at least one of 'id', 'name', or 'isActive' to be defined
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```
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---
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title: Deep Partial Type
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description: Converts all properties of a type, including nested objects, into optional.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,optional
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---
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```ts
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type DeepPartial<T> = {
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[K in keyof T]?: T[K] extends object ? DeepPartial<T[K]> : T[K];
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};
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// Usage:
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type A = {
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name: string;
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details: {
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age: number;
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address: { city: string; zip: string };
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};
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};
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type PartialA = DeepPartial<A>;
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/*
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Type PartialA:
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{
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name?: string;
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details?: {
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age?: number;
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address?: { city?: string; zip?: string };
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};
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}
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*/
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```
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---
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title: Deep Readonly Type
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description: Converts all properties of a type, including nested objects, into readonly.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,readonly
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---
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```ts
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type DeepReadonly<T> = {
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readonly [K in keyof T]: T[K] extends object ? DeepReadonly<T[K]> : T[K];
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};
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// Usage:
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type A = {
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name: string;
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details: {
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age: number;
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address: { city: string; zip: string };
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};
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};
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type ReadonlyA = DeepReadonly<A>;
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/*
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Type ReadonlyA:
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{
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readonly name: string;
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readonly details: {
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readonly age: number;
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readonly address: { readonly city: string; readonly zip: string };
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};
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}
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*/
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```
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---
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title: Deep Required Type
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description: Converts all properties of a type, including nested objects, into required.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,required
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---
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```ts
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type DeepRequired<T> = T extends object
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? { [K in keyof T]-?: DeepRequired<T[K]> }
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: T;
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// Usage:
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type A = {
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id?: string;
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name?: string;
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details?: {
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age?: number;
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address?: { city?: string; zip?: string };
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};
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};
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type RequiredA = DeepRequired<A>;
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// Result: { id: string; name: string; details: { age: number; address: { city: string; zip: string }; }; }
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```
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---
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title: Keys of Type
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description: Extracts keys from an object type that match a specified value type.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition
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---
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```ts
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type KeysOfType<T, U> = { [K in keyof T]: T[K] extends U ? K : never }[keyof T];
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// Usage:
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type A = { name: string; age: number; isActive: boolean, isDeleted: boolean };
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type StringKeys = KeysOfType<A, string>; // "name"
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type BooleanKeys = KeysOfType<A, boolean>; // "isActive" | "isDeleted"
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```
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---
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title: Keys to Optional
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description: Makes only the specified keys of an object type optional.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,optional
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---
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```ts
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type OptionalKeys<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
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// Usage:
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type A = {
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id: string;
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name: string;
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age: number;
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};
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type WithOptionalName = OptionalKeys<A, "name">;
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// { id: string; age: number; name?: string }
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type WithOptionalNameAndAge = OptionalKeys<A, "name" | "age">;
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// Result: { id: string; name?: string; age?: number }
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```
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---
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title: Nullable Keys
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description: Extracts keys from an object type that allow null or undefined values.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,nullable
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---
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```ts
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type NullableKeys<T> = {
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[K in keyof T]: null extends T[K] ? K : undefined extends T[K] ? K : never;
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}[keyof T];
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// Usage:
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type A = {
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id: string;
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name?: string;
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description: string | null;
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};
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type Nullable = NullableKeys<A>; // "name" | "description"
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```
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---
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title: Omit Keys of Type
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description: Removes keys of a specified type from an object type.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,omit,keys
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---
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```ts
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type OmitKeysOfType<T, U> = {
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[K in keyof T as T[K] extends U ? never : K]: T[K];
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};
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// Usage:
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type A = {
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id: string;
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isActive: boolean;
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data: number[];
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};
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type WithoutBoolean = OmitKeysOfType<A, boolean>; // { id: string; data: number[] }
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```
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---
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title: Required Keys
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description: Extracts required keys from an object.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,required
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---
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```ts
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type RequiredKeys<T> = {
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[K in keyof T]-?: {} extends Pick<T, K> ? never : K;
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}[keyof T];
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// Usage:
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type A = {
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id: string;
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name?: string;
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isActive: boolean;
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};
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type ReqKeys = RequiredKeys<A>; // "id" | "isActive"
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```
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---
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title: Union to Intersection
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description: Converts a union type into an intersection type.
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author: aelshinawy
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tags: typescript,helper-types,typedefinition,intersection,union
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---
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```ts
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type UnionToIntersection<U> = (U extends any ? (arg: U) => void : never) extends (arg: infer I) => void
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? I
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: never;
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// Usage:
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type A = { id: string };
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type B = { name: string };
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type C = { age: number };
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type Intersected = UnionToIntersection<A | B | C>;
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// { id: string } & { name: string } & { age: number }
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```

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