TypeScript tip: Try to avoid optional fields
TypeScript tip: Try to avoid optional fields.
They cause two problems:
1. They reduce type safety.
2. There's no type-safe way to enforce when the field should be populated.
Solution: Often optional fields can be eliminated by declaring separate and more specific types.
Principle: The more information we can provide TypeScript, the more it can help us.
The problem is, an optional field doesn't specify when it must be populated.
This creates two risks:
1. An optional field may not be populated when it logically should be.
2. An optional field may be populated when it logically shouldn't be.
An exception: Optional props on React components are fine - as long as they specify a default.
It in TypeScript, optional fields don’t support a default, so I avoid them otherwise.
Here's a wonderful related post by @ploeh that explores this idea further.
The idea is simple - Make impossible states impossible via careful type design.
https://blog.ploeh.dk/2016/02/10/types-properties-software-designing-with-types/