It's a function that takes a ts.TypeChecker
and a ts.Type
and traverses the type building easy-to-use TypeModel
const typeVisitor = (checker: TypeChecker, type: Type): TypeModel => {...}
export type TypeModel =
| TypeModelString
| TypeModelNumber
| TypeModelUnion
| ...
export interface TypeModelString {
readonly kind: "string";
}
export interface TypeModelNumber {
readonly kind: "number";
}
export interface TypeModelUnion {
readonly kind: "union";
readonly types: TypeModel[];
}
...
It's different from Typescript compiler API built-in model by the next properties
- It has a
kind
field (string
,number
,object
) which is string literal union so it allows you to do exhaustive checks - It simplifies the API itself, there's no methods, flags and this kind of stuff, only
kind
and additional data - It has a built-in special types,
array
andtuple
namely, that is kinda tricky to detect using vanilla compiler API
Basically you want to use it along with a compiler API, just using it for the ts.Type
, and using Typescript compiler API for everything else, e.g. emitting new code, analyzing AST etc.
npm i -D ts-type-visitor
# or
yarn add --dev ts-type-visitor