TypeScript: How to Type a Complex Nested Object with Optional Properties Without Losing Type Safety?
I'm refactoring my project and I'm writing unit tests and I'm reviewing some code and I'm maintaining legacy code that I'm attempting to set up I'm currently working on a TypeScript application that involves a deeply nested object structure, where many properties are optional....... I'm trying to define a type for this object that ensures type safety without making the code overly complex. Here's what I have so far: ```typescript interface Address { street: string; city?: string; state?: string; zip?: string; } interface User { id: number; name: string; email?: string; address?: Address; } interface Company { name: string; users: User[]; } ``` This structure works fine, but when I try to access properties like `company.users[0].address.city`, TypeScript raises an error if `address` is `undefined`: ``` Object is possibly 'undefined'. ``` To handle this, I've tried using optional chaining: ```typescript const userCity = company.users[0].address?.city; ``` However, I'm a bit concerned that this might not be the best practice, especially since I need to display a default value if `city` is `undefined`. I've also attempted to define a utility type for optional properties: ```typescript type Optional<T> = { [K in keyof T]?: T[K] }; ``` But this approach feels like it adds unnecessary complexity. Is there a recommended pattern for handling such nested optional properties in TypeScript? I want to ensure that my types are clear and maintainable, while also avoiding excessive runtime checks. Any advice or examples would be greatly appreciated! Additionally, Iām using TypeScript version 4.5.2, and I see that some community suggestions involve using utility types or advanced types, but Iām not sure how to implement those in this context. Is there a better approach? I'm working with Typescript in a Docker container on Windows 10. Thanks for taking the time to read this! I've been using Typescript for about a year now. Has anyone dealt with something similar? This is for a desktop app running on Windows 11. I've been using Typescript for about a year now.