Discussion on: Easy functional programming techniques in TypeScript for everyone

[Amin]

Hi there, great article! Did you know that you can use Object.freeze to prevent mutating an array or an object?

const list = Object.freeze([])

list.push(1)
// Throws an error

[Maciej Sikora]

It will couse runtime exception. So Object.freeze is not useful in terms of TS.

[Amin]

Hi Maciej. You are absolutely right! That's why it is so good coupled with TypeScript which can prevent mutating a freezed object by refusing to transpile the file.

[Maciej Sikora]

Still I see readonly as a tool for the job. Object.freeze is fully run-time thing and it is decoupled from type definition. Declaration of readonly is included into type definition, so it is explicit. I don't think run-time block is needed here.

[Deepu K Sasidharan]

Yes, I thought of writing about it but then missed