Using the Firefox DevTools to Debug fetch() on GitHub

In this video, Dan Callahan shows a real-world example of using the Firefox Developer Tools to help find, file, and fix Bug 1143857: "Fetch does not serialize FormData body; breaks GitHub."

0:13 - The error
0:50 - Using the Network Panel
1:30 - Editing and Resending HTTP Requests
2:02 - Hypothesis: FormData was getting coerced to a String rather than being serialized
2:40 - Prettifying minified JavaScript
3:10 - Setting breakpoints on event handlers
4:57 - Navigating the call stack
7:54 - Setting breakpoints on lines
8:56 - GitHub's FormData constructor
10:48 - Invoking fetch()
11:53 - Verifying the bug by testing fetch() on another domain
12:52 - Checking the docs for fetch()
13:42 - Filing a Gecko bug in Bugzilla
14:42 - The lifecycle of Bug 1143857: New to Duplicate to Reopened to Resolved
15:41 - Verifying a fixed build of Firefox

Links:

[VladFilippov]

Great video Dan! Looking forward to more DevTools videos!

[simoben]

the nightly version redirect the meta data so that the list still reachable well done M8.