Type safety
at runtime
with json decoders
typescript
is not perfect
what's the problem?
underneath, typescript is just
plain javascript
No interfaces
and type aliases
No runtime validation
after transpilation
what's
the solution?
json decoders
elm
ts.data.json
what about ?
Runtype
io-ts
etc...
JsonDecoder.string: Decoder<string>; JsonDecoder.number: Decoder<number>; JsonDecoder.boolean: Decoder<boolean>;
basic decoders
import { JsonDecoder } from 'ts.data.json';
interface Person {
name: string;
}
const personDecoder = JsonDecoder.object<Person>(
{ name: JsonDecoder.string },
'Person'
);
const invalidPerson = { name: 1 };
personDecoder
.decodePromise(invalidPerson)
.then(console.log)
.catch(console.error);
// <Person> decoder failed at key "name"
// with error: 1 is not a valid stringyour turn!
TRY THEM OUT!
KAJETAN ŚWIĄTEK
kajetansw
dev-self-start
Type safety at runtime
By Kajetan Świątek
