express-typed-rpc

WARNING! This repo is still a work in progress. Please contribute if you're interested ❤️

Simple express middleware to easily create a fully-typed JSON API over HTTP on both the server-side and client-side. This project is inspired by tRPC, but much simpler.

Crazy Simple and Easy to Use 😃

Works out of the box with express and Typescript
No magic or black boxes
No code generation or build steps! Works 100% statically via Typescript's infer keyword
No writing type specifications
Minimal configuration
Client included!
Tiny codebase (~50LOC) with minimal dependencies. Written in clean, simple Typescript. Contribute or fork and make it your own.

Make Your Code More Reliable and Go Faster! 🚀

Take advantage of Typescript and turn your runtime errors into compiler-time errors! Inputs and outputs are both fully typed.
Easily unit-test your express handlers since they are now no longer dependent on req and res

Installation

npm i express-typed-rpc

Example Usage

server.ts

import express from 'express';
import { Router } from 'express';
import { createAPI, InferAPI } from 'express-typed-rpc/dist/server';

const apiRouter = Router();

const api = {
    greet: (name: string): string => `Hello, ${name}!`,
    multiply: (args: {a: number, b: number}): number => args.a * args.b
};

createAPI(apiRouter, api);

// Export type for use on client
export type API = InferAPI<typeof api>;

const app = express();

app.use('/api', apiRouter);
app.listen(process.env.PORT || 3000);

dom-client.ts

import {client} from 'express-typed-rpc/dist/client';
import type {API} from '@yourorg/server' 

const greet = async (name: string): Promise<string> => {
    return await client<API['greet']>('greet', name, {
        endpoint: 'https://api.yourdomain.com',
        options: {} // fetch options (window.RequestInit)
    });
};

const multiply = async (numbers: {a: number, b: number}): Promise<number> => {
    return await client<API['multiply']>('multiply', numbers, {
        endpoint: 'https://api.yourdomain.com',
        options: {} // fetch options (window.RequestInit)
    });
};

node-client.ts

import {client} from 'express-typed-rpc/dist/client-node';
import type {API} from '@yourorg/server'

const greet = async (name: string): Promise<string> => {
    return await client<API['greet']>('greet', name, {
        endpoint: 'https://api.yourdomain.com',
        options: {} // https.RequestOptions
    });
};

const multiply = async (numbers: {a: number, b: number}): Promise<number> => {
    return await client<API['multiply']>('multiply', numbers, {
        endpoint: 'https://api.yourdomain.com',
        options: {} // https.RequestOptions
    });
};

You must publish your backend as a private repo (Github Packages is recommended). Only the Typescript types are exported/imported and does not affect runtime. You will enjoy the same performance but with IDE autocompletion, validation, and compile-time TypeScript errors.

Contribution

Please contribute to this project! Issue a PR against main and request review.

Please test your work thoroughly.
Make sure all tests pass with appropriate coverage.

How to build locally

npm i

Running tests

npm test