Why is my Ajax Request Containing dataType: "jsonp" erroring?

Question

I have the following Ajax call:

var baseurl = Office.context.mailbox.restUrl;
var getMessageUrl = baseurl + "/v2.0/me/messages/" + rest_id + "?$select=SingleValueExtendedProperties&$expand=SingleValueExtendedProperties($filter=PropertyId eq 'String 0x007D')";


$.ajax({
        url: getMessageUrl,
        dataType: "jsonp",
        headers: {
            "Authorization": "Bearer " + rest_token,
            "Accept": "application/json; odata.metadata=none"
        },
        error: function (xhr, ajaxOptions, thrownError) {
            $('.resultsScore').text(xhr.statusText);
        }
    }).done(function (item) {

However, this always throws an error (the error function is always entered). If I used dataType: "json", it works fine. What am I doing wrong? Why can I not use jsonp in this way?

`Accept: application/json` is not correct for JSONP. The response to JSONP is JavaScript, not JSON. — Barmar, Sep 23 '20 at 22:11
Thanks, Barmar. However, if I do dataType: "jsonp" and "Accept": "application/json; odata.metadata=none", it still gives the error. Any ideas? — BigDataFiles, Sep 23 '20 at 23:53
Most APIs don't implement JSONP. You can't ask for it if the server doesn't know how to provide it. — Barmar, Sep 23 '20 at 23:56

score -1 · Answer 1 · answered Sep 23 '20 at 21:53

The error is almost certainly because the response isn't JSONP.

There are several reasons that might be. The service you are calling might simply not support it. In addition, JSONP requests do not support the setting of custom headers, so your Authorization will be missing.

Why is my Ajax Request Containing dataType: "jsonp" erroring?

1 Answers1