Union Type to Intersection Type in TypeScript

Last Updated : 10 Jun, 2024

To Transform union type to intersection type we have different approaches. In this article, we are going to learn how to Transform union type to intersection type.

Below are the approaches used to Transform union type to intersection type:

Table of Content

Union Type

A union type in TypeScript allows a variable to have one of several types. It is represented using the | operator.
Example: type Animal = "Dog" | "Cat" | "Bird";
In this example, a variable of type Animal can have the value "Dog", "Cat", or "Bird".

Intersection Type

An intersection type combines multiple types into a single type, representing the combination of all types. It is represented using the & operator.
Example: type Person = { name: string } & { age: number };
In this example, a variable of type Person must have both a name property of type string and an age property of type number.

Using Distributive Conditional Types

Conditional types can be used in a distributive manner to distribute over a union of types, effectively creating an intersection type.

Example: In this example, the UnionToIntersection type uses distributive conditional types to transform a union type into an intersection type. The distributive conditional type operates over each member of the union individually, and the resulting type is the intersection of all the members.

JavaScript

type UnionToIntersection<U> = (     U extends any ? (k: U) => void : never ) extends (k: infer I) => void     ? I     : never;  // Example usage type UnionType = { a: number } | { b: string } | { c: boolean };  type IntersectionType = UnionToIntersection<UnionType>;  // Example object of IntersectionType const myObject: IntersectionType = {     a: 42,     b: "hello",     c: true };  console.log(myObject);

Output:

"a": 42,  
"b": "hello",   
"c": true

Using Conditional Template Literal Types

Conditional template literal types provide a versatile mechanism for manipulating and transforming types in TypeScript. By combining conditional types with template literal types, we can create an elegant solution to convert union types into intersection types.

Example: In this example, we define a type UnionToIntersection that takes a union type U and recursively distributes over each member of the union. The UnionToIntersection type leverages conditional template literal types to iteratively build an intersection type by concatenating individual members of the union.

JavaScript

type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (     (k: infer I) => void) ? I : never;  // Example usage type UnionType = { a: number } | { b: string } | { c: boolean };  type IntersectionType = UnionToIntersection<UnionType>;   const myObject: IntersectionType = {     a: 22,     b: "GFG",     c: true };  console.log(myObject);

Output:

{
  "a": 22,
  "b": "GFG",
  "c": true
}

How to Transform Union Type to Tuple Type in TypeScript ?

amanv09

Improve

Article Tags :

Similar Reads

TypeScript Object Intersection Types

In TypeScript, Object Intersection Types are a way to create new types by combining multiple types into a single type. This is done using the & (ampersand) operator. Intersection types allow you to express that an object must have all the properties and methods of each type in the intersection.

3 min read

How to Return a Union Type in TypeScript ?

In TypeScript, a union type is a powerful way to express a variable that can be one of several types. Union types are used when a function or variable is expected to support multiple types of input. Union types are defined using the pipe (|) symbol between two or more types. This indicates that a va

4 min read

What are intersection types in Typescript ?

In Typescript, Although intersection and union types are similar, they are employed in completely different ways. An intersection type is a type that merges several kinds into one. This allows you to combine many types to create a single type with all of the properties that you require. An object of

3 min read

How to Transform Union Type to Tuple Type in TypeScript ?

In TypeScript, conversion from union type to tuple type consists of mapping each type in the union to a position in the tuple. This process consists of using mapped types or conditional types to perform the transformation. The below methods can be implemented to accomplish this task. Table of Conten

3 min read

TypeScript Extract<Type, Union> Utility Type

In this article, we are going to learn about Extract<Type, Union> utility type in TypeScript, TypeScript is a strongly typed programming language that builds on JavaScript, giving you better tools at any scale. Extract<Type, Union> utility type is used to extract a subset of types from a

4 min read

TypeScript Defining a Union Type

In this article, we are going to learn about Defining a Union Type in Typescript. TypeScript is a popular programming language used for building scalable and robust applications. In TypeScript, a union type allows a variable to have one of several possible types. You can define a union type by using

3 min read

TypeScript Creating Types from Utility Type

TypeScript Creating Types from Utility Type increases the code readability and ease of use when using any complex operations and values, there are different ways to do the type creation with the existing ones. TypeScript Creating Types from Utility Type:Generics: It basically allows us to declare th

3 min read

TypeScript InstanceType<Type> Utility Type

In this article, we are going to learn about InstanceType<Type> Utility Type in Typescript. TypeScript is a popular programming language used for building scalable and robust applications. In TypeScript, the InstanceType<Type> utility type is used to extract the instance type of a constr

3 min read

TypeScript Object Interfaces vs. Intersections

TypeScript offers several features when it comes to defining complex data structures. In TypeScript, Object Interface and Intersections are two different features that serve different purposes when it comes to defining complex data structures. Object InterfacesObject Interfaces are used to define th

3 min read

TypeScript ReturnType <Type> Utility Type

The ReturnType<Type> utility type in TypeScript extracts and infers the return type of a given function type. It enhances type safety and reusability by allowing developers to dynamically determine the type of values returned by functions without manually specifying them. Syntaxtype ResultType

3 min read