In Android I can use OkHttp to read any Html page and scan it for items. Can this be done by
I would to convert the Android app to Ionic.
It looks like that any read of an HTML page with HttpClient will result in a CORS or CORB.
So, I cannot read any HTML page in Ionic?
The same-origin policy generally prevents one origin from reading arbitrary network resources from another origin. In practice, enforcing this policy is not as simple as blocking all cross-origin loads: exceptions must be established for web features, like or which can target cross-origin resources for historical reasons, and for the CORS mechanism which allows some resources to be selectively read across origins.
Certain types of content, however, can be shown to be incompatible with all of the historically-allowed permissive contexts. JSON is one such type: a JSON response will result in a decode error when targeted by the tag, either a no-op or syntax error when targeted by the tag, and so on. The only case where a web page can load JSON with observable consequences, is via fetch() or XMLHttpRequest; and in those cases, cross-origin reads are moderated by CORS.
By detecting and blocking loads of CORB-protected resources early -- that is, before the response makes it to the image decoder or JavaScript parser stage -- CORB defends against side channel vulnerabilities that may be present in the stages which are skipped.
Your requests are blocked even from reading for security reasons. You can establish a session for the API from your server-side and send requests from there. You will need to make sure that every header is correct. This way your server will act as a proxy, but you should avoid doing this if your requests are unwanted by the target API. If there is no harm in doing your requests for the API and you are blocked as a collateral damage, then you can use your server as a proxy.