模块 ringo/promise
允许使用将在未来解决的deferred值。
Class PromiseList
Deferred ()
创建一个代表deferred值的对象。deferred对象有两个属性：一个 promise 对象和一个 resolve() 函数。
promise对象可用于注册promise最终解析时要调用的回调。
resolve函数用于解决promise被执行或失败。
Example
// --- sample output ---
// getDeferredValue() ...
// getDeferredValue() finished after 396 ms
// Resolved promise, got foo
// Total time: 2400 ms
const getDeferredValue = function () {
const deferred = new Deferred();
setTimeout(function() {
deferred.resolve("foo");
}, 2000);
return deferred;
};
const start = Date.now();
console.log("getDeferredValue() ... ");
const def = getDeferredValue();
console.log("getDeferredValue() finished after",
Date.now() - start, "ms");
def.promise.then(function(value) {
console.log("Resolved promise, got", value);
console.log("Total time: ", Date.now() - start, "ms");
});Deferred.prototype. promise
promise对象可用于注册promise最终解析时要调用的回调。
Deferred.prototype. resolve (result, isError)
Resolve the promise.
Parameters
| Object | result | the result or error value |
| Boolean | isError | if true the promise is resolved as failed |
Promise
一个promise对象。 这个类不被导出，创建一个 deferred对象 来创建一个promise.
Promise.prototype. then (callback, errback)
注册回调函数和errback函数，在解析promise时调用。
Parameters
| Function | callback | called if the promise is resolved as fulfilled |
| Function | errback | called if the promise is resolved as failed |
Returns
| Object | a new promise that resolves to the return value of the callback or errback when it is called. |
Promise.prototype. wait (timeout)
等待promise被解决。
Parameters
| Number | timeout | optional time in milliseconds to wait for. If timeout is undefined wait() blocks forever. |
Returns
| Object | the value if the promise is resolved as fulfilled |
Throws
PromiseList (promise...)
PromiseList类允许将几个promise合并为一个。 它表示一个promise，它解析为一个对象数组，每个对象都包含一个值或错误属性，其中包含相应promise参数的值或错误。
PromiseList即使部分或全部部分promise解析为错误，也能成功解析。 处理函数负责检查每个单独的promise结果。
Example
// --- sample output ---
// Done!
// { value: 'i am ok' }
// { value: 1 }
// { error: 'some error' }
let d1 = Deferred(), d2 = Deferred(), d3 = Deferred();
// PromiseList accepts a promise or deferred object
let list = PromiseList(d1.promise, d2, d3);
list.then(function(results) {
console.log("Done!");
results.forEach(function(result) {
console.dir(result);
});
}, function(error) {
console.error("Error :-(");
});
d2.resolve(1);
d3.resolve("some error", true);
d1.resolve("i am ok");Parameters
| Promise... | promise... | any number of promise arguments. |