support typescript loaders

[vankop]

• Operating System: any
• Node Version: any
• NPM Version: any
• webpack Version: @4
• schema-utils Version: latest

Feature Proposal

I'm writing loader on TypeScript and it will be awesome if schema-utils will provide definitions respecting JSON schema specification (see @types/json-schema) + I did not found out (from small documentation on webpack.js.org) is it possible to increase DX (change error message, show possible options, i.e. developer made mistake in option name and I want provide suggestions)

Feature Use Case

Increase DX, TypeScript support

UPD: found out from code that webpack show suggestions depending on provided schema

[alexander-akait]

/cc @sokra should we put here definitions?

[vankop]

@evilebottnawi ping

[alexander-akait]

@vankop can you provide example?

[vankop]

example schema:

import {JSONSchema4, JSONSchema6, JSONSchema7} from "json-schema";
import {ValidationError as AjvValidationError} from 'ajv';

interface ValidationErrorConfiguration {
  name: string,
  baseDataPath: string,
  postFormatter: (formattedError: string, error: AjvValidationError) => string;
}

interface ValidationError {}

declare var validate: {
  (schema: JSONSchema4 | JSONSchema6 | JSONSchema7, options: Array<object> | object, configuration: Partial<ValidationErrorConfiguration>): void;
  ValidationError: typeof ValidationError
}

export = validate;

[alexander-akait]

@vankop why don't put this in https://github.com/DefinitelyTyped/DefinitelyTyped?

[vankop]

I thought using d.ts files for libraries (especially for small libraries) is better. Since it easy to maintain, maybe TypeScript team will implement d.ts file generation from js files as well (I mean types from js-doc), so webpack will be enable to autogenerate all his d.ts

[alexander-akait]

PR welcome 👍

[vankop]

i will check it locally with npm link and make PR later

[alexander-akait]

@vankop can we close issue?

[vankop]

I have tested locally, works fine with esModuleInterop option. As I understand it is required since there is no default export