TypeScript 干预：使用 Byzantium 打破运行时检查成瘾

interface validrabbit {
    username: string;
    password: string;
}
interface invalidrabbit {
    username: number;
    password: string;
}


type validaterabbit<rabbit> = assert<
    //assert that rabbit is of type {username, password}
    is.type<
        user,
        {
            username: string;
            password: string;
        }
    >,
    //custom compile time exceptions
    "trix are for kids. provide a username and password.",
    user
>;

// ha! silly rabbit...
function checkrabbit<t>(rabbit: validaterabbit<t>) {
    // .... protect your trix
}

declare const rabbit1: validrabbit;
declare const rabbit2: invalidrabbit;

checkrabbit(rabbit1);
checkrabbit(rabbit2);
/**        ~~~~~~~~~
 *           └───── type exception! "...provide a username and password"
 */

// define your trust boundaries
type apirequest<request> = assert<
    and<
    is.on<request, "body">,
    or<is.in<request["method"], "post">, is.in<request["method"], "put">>
>;,
    "someone's being naughty with our api"
>;

// now everything inside is type-safe
function handlerequest<r>(req: apirequest<r>) {
    // if it compiles, it's valid
    // if it's valid, it compiles
    // this is the way
}

// before: your cpu crying for help
function validateusermiddleware(req, res, next) {
    try {
        validateid(req.params.id)        // cpu cycle
        validatebody(req.body)           // cpu cycle
        validatepermissions(req.user)    // cpu cycle
        validatetoken(req.headers.auth)  // cpu cycle
        // your cpu is now considering a career change
        next()
    } catch (e) {
        res.status(400).json({ error: e.message })
    }
}

// after: your cpu sending you a thank you note
type validrequest = assert<
    and<
        is.on<request, 'params.id'>,
        is.on<request, 'body'>,
        is.on<request, 'user'>,
        is.on<request, 'headers.auth'>
    >,
    "invalid request shape"
>;

function handlerequest(req: validrequest) {
    // just business logic, no trust issues
}

$ npx jsr add @constantine/byzantium
#or
$ deno add jsr:@constantine/byzantium
#or
$ pnpm dlx jsr add @constantine/byzantium
# ... and yarn, and whatever other package manager
# Now go delete half your test suite