ku / cors-chrome

a chrome extension to skips CORS restriction

cors

A chrome extension which proxies fetch requests without CORS restriction. Works on only localhost.

How to use?

Install chrome extension for your environment

1. Clone this gist
2. Edit "permissions" of manifest.json to fit your environment. Add the domain you want to access to permissions.
3. Open chrome://extensions/
4. Click "Load unpacked extension..."
5. Select the directory where the files are placed

Popsicle icon is by Lee dessert Collection | Noun Project licensed as Creative Commons CCBY.

Define wrapper

Override fetch() with something like

window.fetch = ( function createFetch() {
  let promises = {};
  let _sequence = 0;
  const listener = (ev) => {
    const detail = ev.detail;
    if (detail) {
      const pair = promises[detail.sequence];
      if (pair) {
        delete promises[detail.sequence];
        if (detail.status >= 400) {
          pair.reject(detail.statusText);
        } else {
          pair.resolve(Object.assign(detail, {
            json: () => Promise.resolve(detail.body)
          }));
        }
      }
    }
  }

  document.addEventListener('INSECURE_CORS_RESPONSE', listener, false);

  return function fetch(url, options) {
    const sequence = _sequence++;
    return new Promise( (resolve, reject) => {
      document.dispatchEvent(
        new CustomEvent('INSECURE_CORS_REQUEST', {
          detail: { url, options, sequence },
        }),
      );
      promises[sequence] = { resolve, reject };
    });
  }
})();