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Promise.js

Providing A+ compliant promises with some extras. Based on microPromise (uP)

• Promise.async()
• Promise.async2()
• Promise.join()
• Promise.wrap()
• Promise.spread()
• Promise.timeout()

Promise.async()

Makes a process/function asynchronous. The process may also return a promise itself which to wait on. If the process returns undefined the promise will remain pending.

Example: Make readFileSync async

   fs = require('fs');
   var asyncReadFile = p.async(fs.readFileSync,'./index.js');
   asyncReadFile.then(function(data){
       console.log(data.toString())
   },function(error){
       console.log("Read error:", error);
   });

Promise.async2()

Adapted for processes expecting a callback(err,ret).

Example: make readFile async

   fs = require('fs');
   var asyncReadFile = p.async2(fs.readFile,'./index.js');
   asyncReadFile.then(function(data){
       console.log(data.toString())
   },function(error){
       console.log("Read error:", error);
   });

Promise.join(promises:Array)

Joins promises and assembles return values into an array. If any of the promises rejects the rejection handler is called with the error.

Example: join two promises

   p = Promise();
   a = Promise();
   b = Promise();
   p.join([a,b]).spread(function(x,y){
       console.log('a=%s, b=%s',x,y);
   },function(err){
       console.log('error=',e);
   });
   b.fulfill('world');
   a.fulfill('hello'); // => 'a=hello, b=world' 
   p.resolved; // => ['hello','world']

Promise.wrap(proto:Object)

Wraps a proto

Example: wrap an Array

   p = Promise();
   c = p.wrap(Array);
   c(1,2,3); // => calls constructor and fulfills promise 
   p.resolved; // => [1,2,3]

Promise.spread(onFulfill:Function, onReject:Function)

Spread has the same semantic as then() but splits multiple fulfillment values into separate arguments

Example: Fulfillment array elements as arguments

   var p = Promise();
   p.fulfill([1,2,3]).spread(function(a,b,c){
       console.log(a,b,c); // => '1 2 3'
   });

Promise.timeout(time:Number, callback:Function)

Timeout a pending promise and invoke callback function on timeout. Without a callback it throws a RangeError('exceeded timeout').

Example: timeout & abort()

   var p = Promise();
   p.attach({abort:function(msg){console.log('Aborted:',msg)}});
   p.timeout(5000);
   // ... after 5 secs ... => Aborted: |RangeError: 'exceeded timeout']

Example: cancel timeout

   p.timeout(5000);
   p.timeout(null); // timeout cancelled

License

Copyright (c) 2012 Kaerus (kaerus.com), Anders Elo <anders @ kaerus com>.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.