{"_attachments":{},"_id":"q","_rev":"1578-61f146ba963ca28f5ee3ed92","author":{"name":"Kris Kowal","email":"kris@cixar.com","url":"https://github.com/kriskowal"},"description":"A library for promises (CommonJS/Promises/A,B,D)","dist-tags":{"future":"2.0.3","latest":"1.5.1"},"license":"MIT","maintainers":[{"name":"domenic","email":"domenic@domenicdenicola.com"},{"name":"kriskowal","email":"kris.kowal@cixar.com"}],"name":"q","readme":"[![Build Status](https://secure.travis-ci.org/kriskowal/q.svg?branch=master)](http://travis-ci.org/kriskowal/q)\n[![CDNJS](https://img.shields.io/cdnjs/v/q.js.svg)](https://cdnjs.com/libraries/q.js)\n\n\n \n\n\nIf a function cannot return a value or throw an exception without\nblocking, it can return a promise instead. A promise is an object\nthat represents the return value or the thrown exception that the\nfunction may eventually provide. A promise can also be used as a\nproxy for a [remote object][Q-Connection] to overcome latency.\n\n[Q-Connection]: https://github.com/kriskowal/q-connection\n\nOn the first pass, promises can mitigate the “[Pyramid of\nDoom][POD]”: the situation where code marches to the right faster\nthan it marches forward.\n\n[POD]: http://calculist.org/blog/2011/12/14/why-coroutines-wont-work-on-the-web/\n\n```javascript\nstep1(function (value1) {\n step2(value1, function(value2) {\n step3(value2, function(value3) {\n step4(value3, function(value4) {\n // Do something with value4\n });\n });\n });\n});\n```\n\nWith a promise library, you can flatten the pyramid.\n\n```javascript\nQ.fcall(promisedStep1)\n.then(promisedStep2)\n.then(promisedStep3)\n.then(promisedStep4)\n.then(function (value4) {\n // Do something with value4\n})\n.catch(function (error) {\n // Handle any error from all above steps\n})\n.done();\n```\n\nWith this approach, you also get implicit error propagation, just like `try`,\n`catch`, and `finally`. An error in `promisedStep1` will flow all the way to\nthe `catch` function, where it’s caught and handled. (Here `promisedStepN` is\na version of `stepN` that returns a promise.)\n\nThe callback approach is called an “inversion of control”.\nA function that accepts a callback instead of a return value\nis saying, “Don’t call me, I’ll call you.”. Promises\n[un-invert][IOC] the inversion, cleanly separating the input\narguments from control flow arguments. This simplifies the\nuse and creation of API’s, particularly variadic,\nrest and spread arguments.\n\n[IOC]: http://www.slideshare.net/domenicdenicola/callbacks-promises-and-coroutines-oh-my-the-evolution-of-asynchronicity-in-javascript\n\n\n## Getting Started\n\nThe Q module can be loaded as:\n\n- A ``