Replace Resolver based on jQuery.xhr with fetch.

[dwaite]

• Add 'whatwg-fetch' (browser polyfill) and 'node-fetch' (node.js variant) packages
• Add default_fetcher.ts to export the appropriate fetcher for the environment
• Change code to take an optional fetcher argument (where formerly requestor was taken), and to fall back to the default fetcher
• Remove xhr.ts, node_requestor.ts as no longer used.
• Add toStringMap() to RevokeTokenRequest
• Add test_fetcher with test functions testFetchWithResult and testFetchWithError; these are fetcher implementations that return either the given response body (by stringifying the supplied object) or the given promise rejection.

[dwaite]

Note: I do not know the copyright policy for the project (files are copyright Google, not OIDF) so I added myself as the copyright holder in the header for the new files.

[geminiyellow]

👍

[tikurahul]

Closing this PR given that this is no longer something we want to do.

[jakefeasel]

It would be very useful to have an alternative Requestor implementation that does not require jquery to be available globally. A fetch-based Requestor would be ideal.

[tikurahul]

Yes. It’s not that hard to build such an implementation. We realized that the typings for fetchs assumed a lot of stuff was global which makes it untenable as a interface whole implementation can be provided.

I think using jquery..xhr’s typings are much better suited. It should be easy to provide an implementation of the Requestor that uses fetch.

[jakefeasel]

Yes, I did this in my app by instantiating the BaseTokenRequestHandler like so:

new AppAuth.BaseTokenRequestHandler({
            // fetch-based alternative to built-in jquery implementation
            xhr: function (settings) {
                return new Promise(function (resolve, reject) {
                    fetch(settings.url, {
                        method: settings.method,
                        body: settings.data,
                        mode: 'cors',
                        cache: 'no-cache',
                        headers: settings.headers
                    }).then(function (response) {
                        if (response.ok) {
                            response.json().then(resolve);
                        } else {
                            reject(response.statusText);
                        }
                    }, reject);
                });
            }
        })

With this change, I was able to drop jQuery as a dependency. It would be great if this was an OOTB option.

[tikurahul]

Yes, this is exactly what I was talking about. I could provide another Requestor out of the box. Would that help?

[jakefeasel]

Yes, that would be very helpful. An even more neat trick would be to detect the presence / absence of $.ajax and use that to decide on what would be the best default Requestor.

[tikurahul]

Yes. That would be amazing.

[alxmiron]

Agree. jquery is not suitable for react-based apps

[dwaite]

I wrote this fetch-based version as part of a sample FWIW.

https://github.com/pingidentity/angular-spa-sample/blob/master/src/app/html5_requestor.ts

[tikurahul]

@dwaite Its easy to write something specific for your app / use-case. However there are more things one needs to consider when its a library which could be potentially used by a lot of diverse clients.