window.fetch polyfill

The fetch() function is a Promise-based mechanism for programmatically making web requests in the browser. This project is a polyfill that implements a subset of the standard Fetch specification, enough to make fetch a viable replacement for most uses of XMLHttpRequest in traditional web applications.

Table of Contents

• Read this first
• Installation
• Usage
  • Importing
  • HTML
  • JSON
  • Response metadata
  • Post form
  • Post JSON
  • File upload
  • Caveats
    • Handling HTTP error statuses
    • Sending cookies
    • Receiving cookies
    • Redirect modes
    • Obtaining the Response URL
    • Aborting requests
• Browser Support

Read this first

• If you believe you found a bug with how fetch behaves in your browser, please don't open an issue in this repository unless you are testing in an old version of a browser that doesn't support window.fetch natively. Make sure you read this entire readme, especially the Caveats section, as there's probably a known work-around for an issue you've found. This project is a polyfill, and since all modern browsers now implement the fetch function natively, no code from this project actually takes any effect there. See Browser support for detailed information.

• If you have trouble making a request to another domain (a different subdomain or port number also constitutes another domain), please familiarize yourself with all the intricacies and limitations of CORS requests. Because CORS requires participation of the server by implementing specific HTTP response headers, it is often nontrivial to set up or debug. CORS is exclusively handled by the browser's internal mechanisms which this polyfill cannot influence.

• This project doesn't work under Node.js environments. It's meant for web browsers only. You should ensure that your application doesn't try to package and run this on the server.

• If you have an idea for a new feature of fetch, submit your feature requests to the specification's repository. We only add features and APIs that are part of the Fetch specification.

Installation

npm install whatwg-fetch --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