TypeScript Required Utility Type

In this article, we'll dive deep into a useful but something I rarely see used utility type - Required<Type>.

The Required utility type lets you enforce that all properties are "required" from an existing type and create a new one.

Required in Action

In the Required<Type> syntax, Type is the original type.

This is easier with an example. Given this User type with all optional properties:

interface User {
  id: number?;
  name: string?;
  email: string?;
  age: number?;

Now assume we want to make all the fields required, Required makes our life easier.

const invalidRequiredUser: Required<User>  = { name: 'Niall Maher', email: 'niall.maher@codu.co' }; 
// ❌ This will throw a compile-time error as all properties are required in Required<User>

The above will error as we have not passed all of the values in User. Now let's look at a valid example:

const requiredUser: Required<User> = { id: 123, name: 'Niall Maher', email: 'niall.maher@codu.co', age: 32`` }; 

/* Required<User> behaves as if we typed the following:
interface User {
  id: number;
  name: string;
  email: string;
  age: number;

In this scenario, requiredUser has a new type that enforces all fields as required.

This concept might seem trivial, but when working on large-scale applications with complex data structures, such precise control over your types becomes a game-changer

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Written by Niall Maher

Founder of Codú - The web developer community! I've worked in nearly every corner of technology businesses; Lead Developer, Software Architect, Product Manager, CTO and now happily a Founder.


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