nat64

The CandidType object nat64 corresponds to the Candid type nat64, is inferred to be a TypeScript bigint, and will be decoded into a JavaScript BigInt at runtime.

TypeScript or JavaScript:

import { Canister, nat64, query } from 'azle';

export default Canister({
    getNat64: query([], nat64, () => {
        return 18_446_744_073_709_551_615n;
    }),
    printNat64: query([nat64], nat64, (nat64) => {
        console.log(typeof nat64);
        return nat64;
    })
});

Candid:

service : () -> {
    getNat64 : () -> (nat64) query;
    printNat64 : (nat64) -> (nat64) query;
}

dfx:

dfx canister call candid_canister printNat64 '(18_446_744_073_709_551_615 : nat64)'
(18_446_744_073_709_551_615 : nat64)