Microsoft Edge extensions send different cookies when processing ajax request

Question

I'm converting a chrome extension to edge. However I find that edge send different cookies when processing ajax requests from simple pages and extensions.

Example:

1. Visit https://httpbin.org/cookies/set?bar=foo from address bar. A new cookie called 'bar' with a value of 'foo' was added.

2. In any background page of an edge extension, create a ajax request using fetch

   fetch('https://httpbin.org/cookies',{credentials: 'include'});
   

The debug console shows that edge do not send the 'bar' cookie.

3. Create following ajax request again in background page

   fetch('https://httpbin.org/cookies/set?bar2=foo2',{credentials: 'include'});
   

   Now the 'bar2' cookie has been set, but there is still no 'bar' cookie.

4. Visit https://httpbin.org/cookies again from address bar. There is no 'bar2' cookie.

Am I doing something wrong or it is a bug or feature of edge?

Answer 1

This happens because Edge splits the cookie stores for extension and page contexts. I've heard about it as both of a feature and a bug. If you need to go around that, you can:

• make ajax request in the context script and message the result back to background.html;
• install Insiders Preview with newer Edge (tested on Edge 39.14936), which should append cookies correctly;
• if you just need a cookie value, you can do a browser.cookie.get API call. Won't work with HttpOnly cookies;