Javascript Promise Learning (middle)

After a few days, the promise have a little more understanding.

Recently developed with Angularjs, so studied its $q

function is not very powerful, is a simplified version of the Q.js

Reference to the source code, but my grade is much worse ...

As a study, I rewrote an article myself.

This time is quite neat. The code is less.

$q =function(ASYNCFN) {vardefer =NewDeferred ();            ASYNCFN (Defer.resolve.bind (defer), Defer.reject.bind (defer)); returndefer.promise;        }; $q. Defer=function () {            return NewDeferred ();        }; $q. Reject=function(reason) {vardefer =NewDeferred ();            Defer.reject (reason); returndefer.promise;        }; $q. All=function(values) {vardefer =NewDeferred (); varFinaldatas = []; varCount = 0; Values.foreach (function(value, i) {count++; $q. When (value,function(data) {Finaldatas[i]= data;//load directly by index without ordering separately                    if(--count = = 0) {//One + + one--Cancel each other outdefer.resolve (Finaldatas); }                }, function(reason) {defer.reject (reason);            });            }); returndefer.promise;        }; $q. when=function(value, onfulfilled, onrejected, onnotify) {if(ValueinstanceofPromise)returnValue.then (onfulfilled, onrejected, onnotify); vardefer =NewDeferred ();            Defer.resolve (value); returnDefer.promise.then (onfulfilled, onrejected, onnotify);        }; functionDeferred () { This. Promise =NewPromise (); } Deferred.prototype= {            //resolve reject is almost the same, notify will not be deleted after the callResolvefunction(data) {varPromise = This. Promise; //to delay execution and prevent the then method from setting a callback, you want to resolve the situationSetTimeout (function() {promise.states= "fulfilled";                Promise._processcallback (data); }, 0); }, Reject:function(reason) {varPromise = This. Promise; SetTimeout (function() {promise.states= "Rejected";                Promise._processcallback (reason); }, 0); }, notify:function(data) {varPromise = This. Promise; SetTimeout (function() {promise.states= "Notify"; Promise._processcallback (data,true); }, 0); }, constructor:deferred}//Mainis to save defer, do promise.        functionCallback (Defer, onfulfilled, onrejected, onnotify) { This. defer =defer;  This. onfulfilled =onfulfilled;  This. onrejected =onrejected;  This. onnotify =onnotify; }        functionPromise () { This. states = "Pending";  This. Value =undefined;  This. Reason =undefined;  This. _callbacks = []; } Promise.prototype={then:function(onfulfilled, onrejected, onnotify) {//collect the callbacks, and if states not wait, leave immediately.                vardefer =NewDeferred ();  This. _callbacks.push (NewCallback (Defer, onfulfilled, onrejected, onnotify)); if( This. States!== "Pending") {                    vardata = ( This. states = = = "fulfilled")? This. Value: This. Reason;  This. _processcallback (data); }                returndefer.promise; },            "Catch":function(onrejected) {return  This. Then (NULL, onrejected); },            ' Finally ':function(cleanup) {return  This. Then (cleanup, cleanup); }, _processcallback:function(data, is_keepcallback) {//The data here does not accept promise, lazy did not do. Haha                varPromise = This; if( This. states = = = "Pending")return; varstates = ("on-" + This. States). Tocamelcase (); varPromisecallbacks = This. _callbacks; varLength =promisecallbacks.length;  for(vari = 0, L = promisecallbacks.length; I < L; i++) {                                      varcallback = (is_keepcallback)?Promisecallbacks[i]: Promisecallbacks.shift (); vardefer =Callback.defer; if(G.isfunction (Callback[states])) {//to do error handling.                        Try {                            //Call Callback,                            varReturnValue =Callback[states] (data); //if it's promise, then it's a big move, connecting promise to the past .                            if(returnvalueinstanceofPromise) {Returnvalue.then (Defer.resolve.bind (defer), Defer.reject.bi nd (defer));//bind is used here because the resolve needs to refer to this                            }                            Else {                                //if it's not, the value is passed to the next promise.defer.resolve (returnvalue); }                                                   }                        Catch(e) {defer.reject (e); }                    }                    Else {                        //data is not a function, it goes straight down .defer.resolve (data); }}}, constructor:promise}

Javascript Promise Learning (middle)