| 1 | # inflight
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| 2 |
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| 3 | Add callbacks to requests in flight to avoid async duplication
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| 4 |
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| 5 | ## USAGE
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| 6 |
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| 7 | ```javascript
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| 8 | var inflight = require('inflight')
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| 9 |
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| 10 | // some request that does some stuff
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| 11 | function req(key, callback) {
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| 12 | // key is any random string. like a url or filename or whatever.
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| 13 | //
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| 14 | // will return either a falsey value, indicating that the
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| 15 | // request for this key is already in flight, or a new callback
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| 16 | // which when called will call all callbacks passed to inflightk
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| 17 | // with the same key
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| 18 | callback = inflight(key, callback)
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| 19 |
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| 20 | // If we got a falsey value back, then there's already a req going
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| 21 | if (!callback) return
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| 22 |
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| 23 | // this is where you'd fetch the url or whatever
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| 24 | // callback is also once()-ified, so it can safely be assigned
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| 25 | // to multiple events etc. First call wins.
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| 26 | setTimeout(function() {
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| 27 | callback(null, key)
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| 28 | }, 100)
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| 29 | }
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| 30 |
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| 31 | // only assigns a single setTimeout
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| 32 | // when it dings, all cbs get called
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| 33 | req('foo', cb1)
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| 34 | req('foo', cb2)
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| 35 | req('foo', cb3)
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| 36 | req('foo', cb4)
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| 37 | ```
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