JSON literal typer

There are some tools out there that will produce TypeScript Interfaces from a given JSON structure for you. But they only give you the basic types (string, number, etc.). What if there is an API where you want to get its literal values/types?

Install

# to add to your project 
npm install json-literal-typer
# to use command line interface 
npm install --global json-literal-typer

Demo

There is a live demo at https://json-literal-typer.peppnet.de

Example

Let's assume there is an API for gas stations. It will respond with data like this:

{
  "stations": [
    { "id": 1, "name": "station A", "status": "OPEN", "attributes": ["fast"] },
    {
      "id": 2,
      "name": "station B",
      "status": "OPEN",
      "attributes": ["fast", "24/7"],
      "operator": "Station Corp."
    },
    {
      "id": 3,
      "name": "station C",
      "status": "CLOSED",
      "attributes": [],
      "operator": "ACME Inc."
    }
  ]
}

What you would get from other tools is:

interface Station {
  id: number;
  name: string;
  status: string;
  attributes: string[];
  operator?: string;
}
interface RootObject {
  stations: Station[];
}

Nice. But what if you could get:

interface Stations {
  attributes: ('24/7' | 'fast')[];
  id: 1 | 2 | 3;
  name: 'station A' | 'station B' | 'station C';
  operator?: 'ACME Inc.' | 'Station Corp.';
  status: 'CLOSED' | 'OPEN';
}
 
interface Root {
  stations: Stations[];
}

CLI

npm show json-literal-typer versions --json | json-literal-typer

related or inspiring projects

• json-to-ts - Convert jsons to typescript interfaces
• json2ts - generate TypeScript interfaces from JSON
• quicktype - Generate types and converters from JSON, Schema, and GraphQL
• ts-ast-viewer - TypeScript AST viewer