Created
November 3, 2012 12:01
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Promises API implementation in 1 hour
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| function defer() { | |
| var handlers = []; | |
| var value; | |
| var error; | |
| return { | |
| promise: { | |
| then: function(callback, errback) { | |
| var d = defer() | |
| if (value) { | |
| if (callback) { | |
| try { | |
| d.resolve(callback(value)); | |
| } catch (e) { | |
| d.reject(e); | |
| } | |
| } else { | |
| d.resolve(value); | |
| } | |
| } else if (error) { | |
| if (errback) { | |
| try { | |
| d.resolve(errback(error)); | |
| } catch (e) { | |
| d.reject(e); | |
| } | |
| } else { | |
| d.reject(e); | |
| } | |
| } else { | |
| handlers.push({ | |
| resolved: callback, | |
| rejected: errback, | |
| defered: d | |
| }) | |
| } | |
| return d.promise; | |
| } | |
| }, | |
| resolve: function(val) { | |
| value = val; | |
| handlers.forEach(function(handler){ | |
| try { | |
| if (handler.resolved) { | |
| handler.defered.resolve(handler.resolved(val)); | |
| } else { | |
| handler.defered.resolve(val); | |
| } | |
| } catch (e) { | |
| handler.defered.reject(e); | |
| } | |
| }) | |
| }, | |
| reject: function(err) { | |
| error = err; | |
| handlers.forEach(function(handler){ | |
| try { | |
| if (handler.rejected) { | |
| handler.defered.resolve(handler.rejected(val)); | |
| } else { | |
| handler.defered.reject(val); | |
| } | |
| } catch (e) { | |
| handler.defered.reject(e); | |
| } | |
| }) | |
| } | |
| } | |
| } |
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