# inflight Add callbacks to requests in flight to avoid async duplication ## USAGE ```javascript var inflight = require('inflight') // some request that does some stuff function req(key, callback) { // key is any random string. like a url or filename or whatever. // // will return either a falsey value, indicating that the // request for this key is already in flight, or a new callback // which when called will call all callbacks passed to inflightk // with the same key callback = inflight(key, callback) // If we got a falsey value back, then there's already a req going if (!callback) return // this is where you'd fetch the url or whatever // callback is also once()-ified, so it can safely be assigned // to multiple events etc. First call wins. setTimeout(function() { callback(null, key) }, 100) } // only assigns a single setTimeout // when it dings, all cbs get called req('foo', cb1) req('foo', cb2) req('foo', cb3) req('foo', cb4) ```