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Typescript – make one type equal to another but with its properties being optional

April 13, 2022

I have 2 types:

type Core = {
  a: boolean;
  b: number;
  c: string
}

type CoreOptions = {
  a?: boolean;
  b?: number;
  c?: string;
}

In this example, CoreOptions is meant to have some, none, or all of the properties that Core has depending on the use case, but never to have a property that isn’t in Core.

I am trying to systematically tie them together so that as things evolve and Core gets new properties, I only have to change the type Core.

How can this be achieved?

>Solution :

To use a type, but make all properties optional, TypeScript has a Utility type called Partial. Official Documentation

Example from the TypeScript Documentation:

interface Todo {
  title: string;
  description: string;
}
 
function updateTodo(todo: Todo, fieldsToUpdate: Partial<Todo>) {
  return { ...todo, ...fieldsToUpdate };
}
 
const todo1 = {
  title: "organize desk",
  description: "clear clutter",
};
 
const todo2 = updateTodo(todo1, {
  description: "throw out trash",
});