ReactiveX
RxJs 7 setting X-Requested-With by default when RxJs 6 did not
Describe the bug
Reraise of https://github.com/ReactiveX/rxjs/issues/6663
The X-Requested-With header is still getting set in v7 with default parameters to an AJAX call where with RxJs 6 it did not, constituting a breaking change when using with a server that does not support preflight requests but does correctly return an Access-Control-Allow-Origin.
I've enhanced the reproductions to try show it more clearly in the codepen.
Expected behavior
Default parameter AJAX call to a non-same-origin endpoint which does not support Preflight but does return the correct allow headers to succeed. In other words - do not send a custom header in the request.
Reproduction code
Working: 6.6.7: https://codepen.io/Driskell/pen/yLovOxK
Not working: 7.4.0: https://codepen.io/Driskell/pen/MWvQymO 7.5.2: https://codepen.io/Driskell/pen/PoJyRaz 7.5.4: https://codepen.io/Driskell/pen/jOaGbwX 7.5.6: https://codepen.io/Driskell/pen/poVyyLo 8.0.0-alpha.4: https://codepen.io/Driskell/pen/NWMNNYV
Reproduction URL
No response
Version
7.5.2
Environment
No response
Additional context
No response
I can see the last issue did cause some changes and it seems things are improved but I'm still getting lots of issues around this as it's still unexpected for X-Requested-With to get appended by default.
Hit this again with CORS as there's now an additional header in Access-Control-Request-Headers 😢
Still seeing the rogue header in latest 7 and the new 8 alpha
7.5.6: https://codepen.io/Driskell/pen/poVyyLo 8.0.0-alpha.4: https://codepen.io/Driskell/pen/NWMNNYV