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christianscott/optional-property.ts

Last active December 20, 2018 02:33
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Make properties on an existing type optional
Raw
optional-property.ts
type OptionalProperty<T, P extends keyof T> = {
[K in Exclude<keyof T, P>]: T[K];
} & {
[K in Extract<keyof T, P>]?: T[K];
};
// Example
type Person = { age: number; name: string; country: string; };
const person: OptionalProperty<Person, 'age' | 'country'> = { name: 'Person', age: undefined }; // OK
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