56 lines
1.9 KiB
JavaScript
56 lines
1.9 KiB
JavaScript
define("dojo/when", [
|
|
"./Deferred",
|
|
"./promise/Promise"
|
|
], function(Deferred, Promise){
|
|
"use strict";
|
|
|
|
// module:
|
|
// dojo/when
|
|
|
|
return function when(valueOrPromise, callback, errback, progback){
|
|
// summary:
|
|
// Transparently applies callbacks to values and/or promises.
|
|
// description:
|
|
// Accepts promises but also transparently handles non-promises. If no
|
|
// callbacks are provided returns a promise, regardless of the initial
|
|
// value. Foreign promises are converted.
|
|
//
|
|
// If callbacks are provided and the initial value is not a promise,
|
|
// the callback is executed immediately with no error handling. Returns
|
|
// a promise if the initial value is a promise, or the result of the
|
|
// callback otherwise.
|
|
// valueOrPromise:
|
|
// Either a regular value or an object with a `then()` method that
|
|
// follows the Promises/A specification.
|
|
// callback: Function?
|
|
// Callback to be invoked when the promise is resolved, or a non-promise
|
|
// is received.
|
|
// errback: Function?
|
|
// Callback to be invoked when the promise is rejected.
|
|
// progback: Function?
|
|
// Callback to be invoked when the promise emits a progress update.
|
|
// returns: dojo/promise/Promise
|
|
// Promise, or if a callback is provided, the result of the callback.
|
|
|
|
var receivedPromise = valueOrPromise && typeof valueOrPromise.then === "function";
|
|
var nativePromise = receivedPromise && valueOrPromise instanceof Promise;
|
|
|
|
if(!receivedPromise){
|
|
if(callback){
|
|
return callback(valueOrPromise);
|
|
}else{
|
|
return new Deferred().resolve(valueOrPromise);
|
|
}
|
|
}else if(!nativePromise){
|
|
var deferred = new Deferred(valueOrPromise.cancel);
|
|
valueOrPromise.then(deferred.resolve, deferred.reject, deferred.progress);
|
|
valueOrPromise = deferred.promise;
|
|
}
|
|
|
|
if(callback || errback || progback){
|
|
return valueOrPromise.then(callback, errback, progback);
|
|
}
|
|
return valueOrPromise;
|
|
};
|
|
});
|