typescript-tips

housecor Cory House (@housecor) - October 16, 2022 at 9:29 PM

TypeScript tip:

Avoid making a property optional when the property isn’t valid in a certain case.

Instead, declare 2 separate types, and use Omit to avoid copy/paste.

Example: Many objects lack an id until they’re saved. So declare a separate “Unsaved” type.

#typescript pic.twitter.com/Wzzx3DtYEE

// Avoid making a property optional to support two separate scenarios. // Doing so redunces type safety. type User = { // Making id optional since unsaved users don't have an id yet. 👎 id?: number; name: string; email: string; } // Instead, declare separate types. Then each scenario is fully type safe. 👍 type User = { id: number; name: string; email: string; } // Separate type for unsaved users. // Deriving from the User type via Omit to keep types clean and lean. type UnsavedUser = Omit<User, "id">;

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