typescript-transform-rtti

This transformer emits runtime type information (RTTI) about typescript types.

There's currently just one intrinsic function that emits an array of values about literal unions and const enums, see rtti.d.ts.

rtti.literalsOf<>()

An intrinsic function that gets replaced with a unique set of values about literal unions and const enums per type argument. Don't rely on a particular order.

This is useful for runtime validation of values, e.g. using zod.

export const enum StringBasedEnum {
    one = "1",
    two = "2",
}
z.enum(rtti.literalsOf<StringBasedEnum>() /* << replaced with ["1", "2"] */);

// mixed types:
type Another = "6" | 7;
const literals = rtti.literalsOf<
    StringBasedEnum | Another | "eight" | 5
>(); /* << replaced with ["1", "2", "6", 7, "eight", 5] */

Installation

Use it alongside with typescript and ts-patch as a dev dependency, e.g.

$ npm install typescript-transform-rtti --save-dev

Add it as a plugin in your tsconfig.json:

    "compilerOptions": {
        //...
        "plugins": [{
            "transform": "typescript-transform-rtti"
            // extra options for renaming
            // `rtti` or `literalsOf` here
        }]
    },
    "include": [
        //...
        // Integrate the def file for rtti.*:
        // Copy and tweak to your needs if you change
        // `namespace` or `literalsOf`.
        "./node_modules/typescript-transform-rtti/rtti.d.ts"
    ]

You can customize the transformer with the following options:

• namespace?: string -- Namespace to use for intrinsics, defaults to "rtti".
• literalsOf?: string -- Function name for literals to detect, defaults to "literalsOf".