Today we discuss Type Lookup
This is quite a rare case but if you need to match every element inside a union type by its field type (and you know in advance which one), that’s what you need.
Let’s take a look 👀
This solution looks like what we did in Exclude under the hood:
We used Distributive Conditional Types which helped us filtering out the elements we need.
Here, we need to remove not matched (with
type) elements of a union. Or in other words (if you don’t like double negations as me 😅), we need to pick the union elements of a specific structure. We know in advance that the field is
type. Let’s try:
Also, if you’re familiar with internal type
Extract (it’s the opposite what
Exclude does), you can apply it here:
Great job 🔥
Please, don’t hesitate to go to the test cases in Playground
Have a wonderful day 🌇typescriptmedium