How can I cast custom type to primitive type?
Try:
myRating as unknown as numberAlso, remove | number from your declaration.
Explanation:You cannot cast from a custom to a primitive without erasing the type first. unknown erases the type checking.
Update 2020
TS 3.8 update
now no need to cast using as, it is supported implicitly except in some cases. Where you can do type conversion as given in the accepted answer. Here is a good explanation of type conversion on the typescript.
type Rating = 0 | 1 | 2 | 3 | 4 | 5;let myRating:Rating = 4let rate:number = myRating;Original Answer
I think it is fixed in the typescript update TS 3.5.1
type Rating = 0 | 1 | 2 | 3 | 4 | 5;let myRating:Rating = 4Now
let rate:number = myRating;and
let rate:number = myRating as number;both working fine.