Learn TypeScript 3 by Building Web Applications

io-ts examples

Here's a first example showing how to create a composite validator type:

import * as t from "io-ts"; 
... 
const countryValidator = t.type({ 
    id: t.string, 
    name: t.string, 
    capitalCity: t.string 

}); 

Here, we have used t.type to define a runtime type that combines different properties.

Now let's look at a more concrete example:

import * as t from "io-ts"; import {ThrowReporter} from "io-ts/lib/ThrowReporter"; const countryValidator = t.type({ id: t.string, name: t.string, capitalCity: t.string, }); // extract the corresponding static types interface Country extends t.TypeOf<typeof countryValidator> {} const validCountry:Country = { id: "BE", name: "Belgium", capitalCity: "Brussels" }; const invalidCountry: unknown = { foo: "foo", ...