io-ts-excess

A type for io-ts library, which will fail on any additional properties.

Thanks to @gcanti for the original code.

Warning! Does not work from inside intersection!

Usage

import * as t from "io-ts";
import excess from "io-ts-excess";
 
const C = excess(
  t.type({
    a: t.string,
  }),
);
 
import { PathReporter } from "io-ts/lib/PathReporter";
 
console.log(PathReporter.report(C.decode({ a: "a", b: 1 })));
// [ 'Invalid value {"a":"a","b":1} supplied to : { a: string }, excess properties: ["b"]' ]

TODO

• Make it to work inside intersection. The following code does not work for now:

const I = t.intersection([C, t.type({ b: t.number })])
 
console.log(PathReporter.report(I.decode({ a: 'a', b: 1 })))
// [ 'Invalid value {"a":"a","b":1} supplied to : { a: string }, excess properties: ["b"]' ]