Subset of AbortController sufficient for the needs of mw.Api.
Used by mw.Api#ajax, mw.Api#get, mw.Api#post and related methods.
It may be used as a fallback on browsers that don't support DOM AbortController.
However, it's not compliant with the spec, and can't be used as a polyfill for
AbortController with fetch() or anything else.
Aborting requests this way is somewhat verbose in simple cases, see
mw.Api~AbortablePromise for an alternative style. However, it is much less verbose
when chaining multiple requests and making the whole chain abortable, which would otherwise
require carefully keeping track of the "current" promise at every step and forwarding the
.abort() calls (see T346984), and it's the only style that is fully compatible with native
promises (using async/await).
Cancelling an API request (using AbortController)
const api = new mw.Api();
const abort = new AbortController();
setTimeout( function() { abort.abort(); }, 500 );
api.get( { meta: 'userinfo' }, { signal: abort.signal } ).then( ... );Cancelling chained API requests
const api = new mw.Api();
const abort = new AbortController();
setTimeout( function() { abort.abort(); }, 500 );
const options = { signal: abort.signal };
api.get( { meta: 'userinfo' }, options ).then( function ( userinfo ) {
const name = userinfo.query.userinfo.name;
api.get( { list: 'usercontribs', ucuser: name }, options ).then( function ( usercontribs ) {
console.log( usercontribs.query.usercontribs );
} );
} ).catch( console.log );
// => DOMException: The operation was aborted.Cancelling chained API requests (using await)
const api = new mw.Api();
const abort = new AbortController();
setTimeout( function() { abort.abort(); }, 500 );
const options = { signal: abort.signal };
const userinfo = await api.get( { meta: 'userinfo' }, options );
// throws DOMException: The operation was aborted.
const name = userinfo.query.userinfo.name;
const usercontribs = await api.get( { list: 'usercontribs', ucuser: name }, options );
console.log( usercontribs.query.usercontribs );Cancel the promises using this controller's signal,
rejecting them with the given reason and stopping related async operations.