Network Processor Module


    2.5.4 • Public • Published

    funtch - Functional Fetch

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    Fetch based on isomorphic-fetch with functional and customizable behavior.

    Getting started

    Add dependency to your project

    npm i -S funtch


    Full documentation is available here.

    Full usage example in example folder


    import funtch from 'funtch';
    funtch.get('').then((data) => doSomething(data));


    const funtch = require('funtch').default;
    funtch.get('').then((data) => doSomething(data));


    You can send HTTP requests from common verbs by invoking the following methods from funtch:

    Methode name Params Description
    get url: String
    query: Object/Map
    Perform a GET with optional query params
    post url: String
    body: Any
    Perform a POST with given body and Content-type guessed from param
    put url: String
    body: Any
    Perform a PUT with given body and Content-type guessed from param
    patch url: String
    body: Any
    Perform a PATCH with given body and Content-type guessed from param
    delete url: String Perform a DELETE

    If default pattern doesn't match your needs, you can build a step by step request by invoking funtch.url(url: String) and applying following methods:

    Method name Params Description
    query query: Object/Map Append query params when requesting
    header key: String
    value: String
    Add HTTP header
    auth value: String Add Authorization Header with given value
    contentJson Add Content-type: application/json header
    contentText Add Content-type: text/plain header
    guessContentType body: Any Guess content type by checking if body is a JSON. If true, content is set to JSON, otherwise to text
    acceptJson Add Accept: application/json header
    acceptText Add Accept: text/plain header
    contentHandler callback: func(response) See content handler
    errorHandler callback: func(response, contentHandler) See error handler
    abortHandler callback: func(error) Callback method when request is aborted
    fullResponse Return complete response with {status, headers, data}, instead of just raw data by default
    body body: Any
    guess: Boolean default true
    Set body content of request, and guessing content on the fly
    get Set method to GET and send request
    post body: Any Set method to POST, add body if provided with content guess and send request
    put body: Any Set method to PUT, add body if provided with content guess and send request
    patch body: Any Set method to PATCH, add body if provided with content guess and send request
    delete Set method to DELETE and send request
    method method: String Set HTTP method to given value
    send Send request as it
    abort Abort request

    All these methods, except abort, are chainable and once send is called, the result is a Promise.

    const fetchPromise = funtch
      .auth('Basic SECRET')
      .post({ star: true });
      .then((data) => console.log(data))
      .catch((err) => console.error(data));

    Cancelable request can be done this way.

    const fetchRequest = funtch
      .url('') // 10 seconds delay
      .abortHandler((e) => console.warn(`Request was aborted: ${}`));

    You can create a pre-configured builder, in order to avoid repeating yourself, by passing an object to the withDefault method with keys as the config function name.

    const funtcher = funtch.withDefault({
      baseURL: '',
      auth: 'github SecretToken',
      fullResponse: true,
      contentJson: true,
    funtcher.get('/user/keys').then((response) => doSomething(;
      .post('/user/keys', 'my-ssh-key')
      .then((response) => doSomething(;

    Error Handling

    By default, funtch will rejects promise with a full response describing error if HTTP status is greater or equal than 400. This object contains HTTP status, response headers and data (in plain text or JSON, according to content handler).

      status: 404,
      headers: {
        'content-length': '19',
        'content-type': 'text/plain; charset=utf-8',
        date: 'Sat, 06 May 2017 11:58:38 GMT',
        'x-content-type-options': 'nosniff',
        connection: 'close'
      data: '404 page not found',


    Custom content handler

    By default, fetch exposes only two methods for reading content : text() and json(). Instead of juggling with these methods, funtch return content by examining Content-Type header and call one of the two methods.

    You can easily override default content handler by calling content() on the build. The content handler method accepts a reponse and return a Promise. Method is also passed to error handler method, in order to read content while identifying error.

    Below an example that parse XML response.

    import funtch { MEDIA_TYPE_JSON, CONTENT_TYPE_HEADER } from 'funtch';
    const contentTypeJsonRegex = new RegExp(MEDIA_TYPE_JSON, 'i');
    const contentTypeXmlRegex = /application\/xml/i;
    function xmlContent(response) {
      if (contentTypeJsonRegex.test(response.headers.get(CONTENT_TYPE_HEADER))) {
        return response.json();
      return new Promise(resolve => {
        response.text().then(data => {
          if (contentTypeXmlRegex.test(response.headers.get(CONTENT_TYPE_HEADER))) {
            resolve(new DOMParser().parseFromString(data, 'text/xml'));

    Custom error handler

    By default, fetch returns a valid Promise without considering http status. Funtch error handler is called first, in this way, you can identify an error response and reject the Promise. By default, if HTTP status is greather or equal than 400, it's considered as error.

    You can easyly override default error handler by calling errorHandler() on the builder. The error handler method accepts a response and a content handler, and return a Promise. You can reimplement it completely or adding behavior of the default one.

    Below an example that add a toString() behavior.

    import funtch, { errorHandler } from 'funtch';
    function errorWithToString(response) {
      return new Promise((resolve, reject) =>
          .catch((err) =>
              toString: () => {
                if (typeof err.content === 'string') {
                  return err.content;
                return JSON.stringify(err.content);
      .catch((err) => console.log(String(err)));


    npm i funtch

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