今天从GIT源码库中下载了promise.js，发现该源码是基于Web前端JavaScript写的，并不能直接用于nodejs。还好代码不是很多，也不是很复杂。经过分析整合，将其实现为nodejs的一个框架，代码如下：
(function(){ /** * Copyright 2012-2013 (c) Pierre Duquesne <stackp@online.fr> * script: promise.js * description: promises的nodejs模块 * modified: https://github.com/stackp/promisejs * authors: alwu007@sina.cn * */ var Promise = exports.Promise = function(){ this._callbacks = []; }; Promise.prototype.then = function(func, context){ //处理回调结果的方法 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; }; })();
另附测试代码如下：
/** * script: test.js * description: promise.js测试代码 * */ 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); });
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