fetch-har

Make a fetch request from a HAR definition.

Features

• Supports Node 18+
• Natively works in all browsers that support fetch without having to use any polyfils.
• Tested across Chrome, Safari, Firefox on Mac, Windows, and Linux.
• Requests can be mocked with msw or fetch-mock (though the latter does not appear to be maintained).

Installation

npm install --save fetch-har

Usage

import fetchHAR from 'fetch-har';
// const fetchHAR = require('fetch-har');

const har = {
  log: {
    entries: [
      {
        request: {
          headers: [
            {
              name: 'Authorization',
              value: 'Bearer api-key',
            },
            {
              name: 'Content-Type',
              value: 'application/json',
            },
          ],
          queryString: [
            { name: 'a', value: 1 },
            { name: 'b', value: 2 },
          ],
          postData: {
            mimeType: 'application/json',
            text: '{"id":8,"category":{"id":6,"name":"name"},"name":"name"}',
          },
          method: 'POST',
          url: 'https://httpbin.org/post',
        },
      },
    ],
  },
};

fetchHAR(har)
  .then(res => res.json())
  .then(console.log);

API

Options

userAgent

A custom User-Agent header to apply to your request. Please note that browsers have their own handling for these headers in fetch() calls so it may not work everywhere; it will always be sent in Node however.

await fetchHAR(har, { userAgent: 'my-client/1.0' });

files

An optional object map you can supply to use for multipart/form-data file uploads in leu of relying on if the HAR you have has data URLs. It supports Node file buffers and the File API.

await fetchHAR(har, {
  files: {
    'owlbert.png': await fs.readFile('./owlbert.png'),
    'file.txt': document.querySelector('#some-file-input').files[0],
  },
});

If you don't supply this option fetch-har will fallback to the data URL present within the supplied HAR. If no files option is present, and no data URL (via param.value) is present in the HAR, a fatal exception will be thrown.

init

This optional argument lets you supply any option that's available to supply to the Request constructor.

await fetchHAR(har, {
  init: {
    headers: new Headers({
      'x-custom-header': 'buster',
    }),
  },
});

❗ Note that if you supply body or credentials to this option they may be overridden by what your HAR requires.