Fatcher

Send fetch requests gracefully in browsers and Node.js

Introduction

Fatcher is a lightweight HTTP request library based on the native fetch API. It works seamlessly in both browsers and Node.js environments.

Features

• Fully compatible with the Fetch API
• Zero dependencies
• Less than 1kb
• Works in Node.js and all modern browsers
• Composable middleware
• Streaming API support

Compatibility

Platform	Version
Chrome	>= 66
Firefox	>= 65
Safari	>= 12.1
Edge	>= 16
Opera	>= 53
Internet Explorer	Not Supported
Node.js	>= 18.0.0

Installation

NPM

npm install fatcher

CDN

<script src="https://cdn.jsdelivr.net/npm/fatcher/dist/fatcher.min.js"></script>
<script>
  Fatcher.fatcher('xxx', {}).then(response => {
    console.log(response);
  });
</script>

Quick Start

import { fatcher } from 'fatcher';

const init: RequestInit = {};
fatcher('https://foo.bar', init);

// equivalent to native fetch
fetch('https://foo.bar', init);

Middlewares

Fatcher uses a middleware system similar to Koa.

export interface FatcherOptions extends RequestInit {
  middlewares?: FatcherMiddlewares | FatcherMiddlewares[];
}

export interface FatcherContext extends Omit<FatcherOptions, 'middlewares'> {
  request: Request;
}

export type FatcherFunctionalMiddleware = (
  request: FatcherContext,
  next: (context?: Partial<FatcherContext>) => Promise<FatcherResponse> | FatcherResponse,
) => Promise<FatcherResponse> | FatcherResponse;

export type FatcherMiddleware = {
  name: string;
  use: FatcherFunctionalMiddleware;
};

• FunctionalMiddleware runs every time it is used.
• ObjectMiddleware is registered only once, respecting the registration order.

Custom Middleware

// fatcher.d.ts
import 'fatcher';

declare module 'fatcher' {
  // expand fatcher options for custom options
  interface FatcherOptions {
    baseUrl?: number;
  }
}

// middleware.ts
import { defineMiddleware } from 'fatcher';
const baseUrlMiddleware = defineMiddleware({
  name: 'base-url',
  use: async (context, next) => {
    const target = `${context.baseUrl}/${context.url}`;
    return next({ request: new Request(target, context.request), url: target });
  },
});

// api.ts
fatcher('/foo.bar', {
  baseUrl: 'https://api.example.com',
}).then(response => {
  // do something
});

Examples

Logger Middleware

import { defineMiddleware } from 'fatcher';

const logs = defineMiddleware(async (request, next) => {
  const startTime = Date.now();

  const response = await next();

  console.log(`Request spent ${Date.now() - startTime}ms`);
  return response;
});

fatcher('https://foo.bar', { middlewares: [logs] }); // Request spent 20 ms

Custom Request

import { defineMiddleware } from 'fatcher';

const request = defineMiddleware({
  name: 'my-custom-request',
  use: async context => {
    const response = await myFetch(context.url);
    return response;
  },
});
// custom request should register at last
fatcher('https://foo.bar', { middlewares: [request] });

Request Interceptor

import { defineMiddleware } from 'fatcher';

const requestInterceptor = defineMiddleware({
  name: 'request-interceptor',
  use: async (context, next) => {
    const accessToken = localStorage.get('AccessToken');

    if (accessToken) {
      context.request.headers.set('Authorization', accessToken);
    }

    return next();
  },
});

Response Interceptor

import { defineMiddleware, fatcher } from 'fatcher';

const responseInterceptor = defineMiddleware({
  name: 'response-interceptor',
  use: async (context, next) => {
    const response = await next();

    // rewrite response body
    return new Response('success', response);
  },
});

fatcher('https://foo.bar', {
  middlewares: [responseInterceptor],
}).then(response => {
  const text = await response.text();
  console.log(text); // 'success'2
});

Video Transformer

// fatcher.d.ts
import 'fatcher';

declare module 'fatcher' {
  interface FatcherResponse {
    getMp4: () => Promise<File>;
  }
}

// middleware.ts
import { defineMiddleware, fatcher } from 'fatcher';

const videoTransformer = defineMiddleware({
  name: 'video-transformer',
  use: async (context, next) => {
    const response = await next();

    const videoResponse = response.clone();

    response.getMp4 = () => {
      return new Promise((resolve, reject) => {
        // video transform
        console.log(videoResponse);
      });
    };

    return response;
  },
});

// api.ts
const response = await fatcher('https://video.examples.com/foo.avi', {
  middlewares: [videoTransformer],
});

const mediaSource = new MediaSource();
const url = URL.createObjectURL(mediaSource);
mediaSource.onsourceopen = async () => {
  // read response readableStream for data;
};
const video = document.querySelector('#video');
video.src = url;

const transformedFile = await response.getMp4();
// download mp4 file

Packages

Package	Version
@fatcherjs/middleware-aborter
@fatcherjs/middleware-cache
@fatcherjs/middleware-form-data
@fatcherjs/middleware-json
@fatcherjs/middleware-parameter
@fatcherjs/middleware-progress
@fatcherjs/middleware-exception

License

MIT