Teleman

A tiny (~2kb after gzipped) fetch API wrapper.

Features

• Tiny, only about 2kb after gzipped.
• Support middleware.
• Return decoded response body.
• Handle response.ok for you.

Installation

npm i teleman

NOTE: The code is written in ES2020 syntax and not transpiled. To use it in old browsers, you should transpile the code using tools such as Babel.

Usage

import Teleman from 'teleman'

async function main() {
  const api = new Teleman({
    base: 'http://api.example.com'
  });

  const article = await api.get('/articles', { id: 123 });

  // post JSON
  await api.post('/articles', { title: 'Hello', content: '# Hello' });

  // post with Content-Type: multipart/form-data
  await api.post('/upload', new FormData(document.forms[0]));
}

Singleton

You can also use Teleman directly without creating an instance.

import { teleman } from 'teleman';

teleman.get(url, query, options);
teleman.post(url, body, options);
teleman.put(url, body, options);
teleman.patch(url, body, options);
teleman.delete(url, query, options);
teleman.head(url, query, options);
teleman.purge(url, query, options);
teleman.use(middleware);

Constructor

new Teleman({ base, headers })

Creates a Teleman instance.

base

String. Optional. Base URL. In browser, it's default value is document.baseURI.

headers

Object. Optional. Default headers. It can be a simple key-value object or Headers object.

Methods

instance.fetch()

instance.fetch(url, {
  method = 'GET',
  base = this.base,
  headers,
  query,
  params = {},
  body,
  use = this.middleware,
  ...rest 
} = {})

Parameters

url

String. The URL of the request. If it's a relative URL, it's relative to base parameter.

base

String. Base URL. The request URL will be new URL(url, base).

method

String. HTTP methods. GET, POST, PUT, PATCH, DELETE, HEAD, PURGE. Defaults to 'GET'.

headers

Object | Headers. HTTP headers. It will be merged with instance's default headers.

query

String | Object | Array | URLSearchParams. The query string appends to the URL. It takes the same format as URLSearchParams constructor's param.

params

Object. URL path params.

instance.fetch('/articles/:id', { params: { id: 1 } })

It will use encodeURIComponent() to encode the values.

body

Object | FormData | Blob | BufferSource | URLSearchParams | String. The request body. If the body is a plain object, it will be converted to other type according to content-type of headers:

• not set: to JSON string, and set content-type to application/json.
• application/json: to JSON string.
• multipart/form-data: to FormData.
• application/x-www-form-urlencoded: to URLSearchParams.

use

Array<Middleware>. Middleware functions to use. Defaults to instance.middleware array.

...rest

Other parameters will be set into the context object.

Return Value

instance.fetch() returns a promise.

According to content-type header of the response, it will resolve/reject (depends on response.ok) to different types:

• application/json: response.json()
• text/*: response.text()
• Others: the response object as is.

If any error occurs, the promise will be rejected with that error.

Shortcut methods

instance.get(url, query, options)
instance.post(url, body, options)
instance.put(url, body, options)
instance.patch(url, body, options)
instance.delete(url, query, options)
instance.head(url, query, options)
instance.purge(url, query, options)

instance.use(middleware)

Add the given middleware to instance.middleware array. It returns this so is chainable.

Parameters

middleware

Function. The middleware function to use.

instance
  .use(async(ctx, next) => {
    try {
      return await next();
    } catch (e) {
      alert(e?.message || 'fetch failed');
      throw e;
    }
  });
  .use(async(ctx, next) => {
    const start = Date.now();
    const data = await next();
    const ms = Date.now() - start;
    console.log(`${ctx.options.method} ${ctx.url.href} - ${ms}ms`);
    
    // you can modify the data then return it
    return {
      ...data,
      foo: data.foo || 0
    };
  })

ctx

{
  url, // URL object
  options: { method, headers, body },
  response, // available after `await next()`
  ...rest // additional parameters passed from `instance.fetch()` options
}

url and options will be used to call the fetch() function:

fetch(ctx.url.href, ctx.options)

You can modify the context properties to interfere the request and response.

next

A middleware function should receive the response body from next(), and can optionally modify the data. Finally it should return the data.

License

MIT