a wrapper for node-fetch

a simple wrapper for node-fetch, with support for timeout and retry. once enabled (maxAttempts set to > 1), it will

• retry when request times out (this is unchangeable).
• retry when request matches specific user-defined condition.

installation

npm install node-fetch-wrapper

test

npm test

general usage

// init a wrapper with base url http://example.com 
const FetchWrapper = require('node-fetch-wrapper');
const wrapper = new FetchWrapper('http://example.com', {
  // each request's timeout is 15 seconds
  timeout: 15000,
  // will try 3 times before finish
  maxAttempts: 3
  // wait for 1 seconds after each trial
  interval: 1000,
  // show debug info
  verbose: true,
  // retry on which condtion,
  retryCondition: defaultRetryCondition,
  // this function will be called before each retrying attempts. default unassigned.
  retryCallback: function (res) {
    console.log('callbacked');
  }
});

by default, the retryCondition has value:

function defaultRetryCondition(res) {
  const shouldRetryStatus =
    (res.status >= 100 && res.status <= 199) ||
    (res.status === 429) ||
    (res.status >= 500 && res.status <= 599);
  return shouldRetryStatus;
}

example

basically, this module acts like node-fetch (same input/output) with some additional support for timeout/retry

// identical to fetch('http://example.com/data')
wrapper.get('data');

// identical to fetch('https://example.com/write', { method: 'post', body: 'some body'}).
// note: general setting can be overwritten in specific request
wrapper.post('write', {
  body: 'some body',
  maxAttempts: 5
  retryCondition: function(res) {
    return res.body === 'fail';
  }
});

this module can also be used specifically for json:

const jsonWrapper = new FetchWrapper.json('http://example.com', {
  // each request's timeout is 15 seconds
  timeout: 15000,
  // will try 3 times before finish
  maxAttempts: 3
  // wait for 1 seconds after each trial
  interval: 1000,
  // show debug info
  verbose: true,
  // retry on which condtion,
  // default
  retryCondition: defaultRetryCondition
});

remember to specify json in the request, otherwise error will be thrown

const res = jsonWrapper.post('write', {
  body: 'some body',
  maxAttempts: 5
  json: {
    key1: 'value1'
  }
});

this does additional work that calls res.json() and assign the body back to res object.