Types of fetch responses

[gw1500se]

I can't find this documented any where but what responses are available other than json? I have this function:

function requests(url) {
   return fetch(url).catch(function(error) {
      return(null);
   })
   .then(function(response) {
      if (response==null) {
        return(null);
      }
      else if (!response.ok) {
        console.log("caught error: "+response.status);
      }         
       try {
          return response.json();
       } catch(e) {
         return resonse.html();
       }
   });
}

The response can be either json or html. When html results I get an error:

VM13:1 Uncaught (in promise) SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

How do I tell the difference since try/catch doesn't work? TIA.

 

[Barand]

The ones I'm aware of (for ajax anyway) are

• JSON
• TEXT
• HTML

[requinix]

55 minutes ago, gw1500se said:

I can't find this documented any where

Really?

https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API
https://developer.mozilla.org/en-US/docs/Web/API/Response

[kicken]

3 hours ago, gw1500se said:

what responses are available other than json?

The response data could be anything.  JSON is common so there's a method on the response object to parse it, but you could get whatever data you wanted as either text or binary data.

You should be looking at the Content-type header to find out what the type is and react accordingly.

3 hours ago, gw1500se said:

since try/catch doesn't work?

Because those functions immediately return a promise, which is an action which won't fail.  The failure comes later and the promise is rejected, which you handle with .catch() as described in your other thread.

[gw1500se]

17 hours ago, requinix said:

Really?

https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API
https://developer.mozilla.org/en-US/docs/Web/API/Response

Yes, really. Those never showed up in any of my searches. Thanks for the links.

Edited August 21, 2022 by gw1500se