今天從GIT源碼庫中下載了promise.js，發現該源碼是基於Web前端JavaScript寫的，並不能直接用於nodejs。還好代碼不是很多，也不是很複雜。經過分析整合，將其實現為nodejs的一個框架，代碼如下：
(function(){/*** Copyright 2012-2013 (c) Pierre Duquesne <[email protected]>* script: promise.js* description: promises的nodejs模塊* modified: https://github.com/stackp/promisejs* authors: [email protected]* */var Promise = exports.Promise = function(){ this._callbacks = [];};Promise.prototype.then = function(func, context){ //處理回調結果的方法function doCallbackResults(r) { if (r instanceof Promise) { r.then(function(err, values){ p.done(err, values); }); } else { p.done(null, r); } } var p = new Promise(); if (this._isdone) { var results = func.apply(context, this.results); doCallbackResults(results); } else { this._callbacks.push(function(){ var results = func.apply(context, arguments); doCallbackResults(results); }); } return p;};Promise.prototype.done = function(){ this.results = arguments; this._isdone = true; for (var i=0; i<this._callbacks.length; i++) { this._callbacks[i].apply(null, arguments); } this._callbacks = [];};Promise.join = function(promises){ var p = new Promise(); var results = []; if (!promises || !promises.length) { p.done(results); return p; } var numdone = 0; var total = promises.length; function notifier(i) { return function() { numdone += 1; results[i] = Array.prototype.slice.call(arguments); if (numdone === total) { p.done(results); } }; } for (var i = 0; i < total; i++) { promises[i].then(notifier(i)); } return p;};Promise.chain = function(funcs, args) { var p = new Promise(); if (!funcs || !funcs.length) { p.done.apply(p, args); } else { funcs[0].apply(null, args).then(function(){ funcs.splice(0, 1); Promise.chain(funcs, arguments).then(function(){ p.done.apply(p, arguments); }); }); } return p;};})();另附測試代碼如下：
/*** script: test.js* description: promise.js測試代碼* */var promise = require('./mypromise');function asyncfoo() { var p = new promise.Promise(); setTimeout(function(){ p.done(); }, 1000); return p;}function syncfoo() { var p = new promise.Promise(); p.done(); return p;}var o = {};/*asyncfoo().then(function(){ return 'Raymond';}, o).then(function(err, name){ o.name = name; return asyncfoo().then(asyncfoo).then(function(){ return asyncfoo().then(asyncfoo).then(function(){ return 18; }); });}, o).then(function(err, age){ o.age = age; return asyncfoo().then(asyncfoo).then(function(){ return asyncfoo().then(asyncfoo).then(function(){ return 'boy'; }); }).then(function(err, sex){ return sex; });}).then(function(err, sex){ o.sex = sex; return 'Hello, world!';}).then(function(err, say){ o.say = say; console.dir(o);});syncfoo().then(function(){ return 'Raymond';}, o).then(function(err, name){ o.name = name; return syncfoo().then(syncfoo).then(function(){ return syncfoo().then(syncfoo).then(function(){ return 18; }); });}, o).then(function(err, age){ o.age = age; return asyncfoo().then(asyncfoo).then(function(){ return asyncfoo().then(asyncfoo).then(function(){ return 'boy'; }); }).then(function(err, sex){ return sex; });}).then(function(err, sex){ o.sex = sex; return 'Hello, world!';}).then(function(err, say){ o.say = say; console.dir(o);});*/function asyncfoo1(){ var p = new promise.Promise(); setTimeout(function(){ p.done(null, 'Raymond'); }, 1000); return p;}function asyncfoo2(err, name){ o.name = name; var p = new promise.Promise(); setTimeout(function(){ p.done(null, 18); }, 1000); return p;}function asyncfoo3(err, age){ o.age = age; var p = new promise.Promise(); setTimeout(function(){ p.done(null, 'boy'); }, 1000); return p;}function asyncfoo4(){ var p = new promise.Promise(); setTimeout(function(){ p.done(null, 'Hello, world!'); }, 1000); return p;}promise.Promise.chain([asyncfoo1, asyncfoo2, asyncfoo3]).then(function(err, sex){ o.sex = sex; return asyncfoo4();}).then(function(err, say){ o.say = say;}).then(function(){ console.dir(o);});