fetch-google-apps-script-ponyfill

A ponyfill that makes the browser Promise-based fetch() function to work in Google Apps Script. This is a fork of https://github.com/github/fetch where some parts of this implementation come from.

Installation

npm install fetch-google-apps-script-ponyfill --save

As an alternative to using npm, you can obtain fetch.umd.js from the [Releases][] section. The UMD distribution is compatible with AMD and CommonJS module loaders, as well as loading directly into a page via <script> tag.

Usage

For a more comprehensive API reference that this ponyfill supports, refer to https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch.

Importing

If you are using a build pipeline for your Google Apps Script code you can import it as a module.

import { fetch as fetchGoogleAppsScriptPonyfill } from 'fetch-google-apps-script-ponyfill';
 
fetchGoogleAppsScriptPonyfill(...);

Or when importing this as a separate script then just access the global function directly

function getFetch() {
  return fetchGoogleAppsScriptPonyfill.fetch;
}
getFetch()(...);

JSON

fetch('/users.json')
  .then(function(response) {
    return response.json()
  }).then(function(json) {
    console.log('parsed json', json)
  }).catch(function(ex) {
    console.log('parsing failed', ex)
  })

Caveats

The Promise returned from fetch() won't reject on HTTP error status even if the response is an HTTP 404 or 500. Instead, it will resolve normally, and it will only reject on network failure or if anything prevented the request from completing.
Not all Fetch standard options are supported in this polyfill. For instance, redirect and cache directives are ignored.

Handling HTTP error statuses

To have fetch Promise reject on HTTP error statuses, i.e. on any non-2xx status, define a custom response handler:

function checkStatus(response) {
  if (response.status >= 200 && response.status < 300) {
    return response
  } else {
    var error = new Error(response.statusText)
    error.response = response
    throw error
  }
}
 
function parseJSON(response) {
  return response.json()
}
 
fetch('/users')
  .then(checkStatus)
  .then(parseJSON)
  .then(function(data) {
    console.log('request succeeded with JSON response', data)
  }).catch(function(error) {
    console.log('request failed', error)
  })