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63 lines
2.1 KiB
63 lines
2.1 KiB
10 years ago
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# some
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Short-circuited async Array.prototype.some implementation.
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Serially evaluates a list of values from a JS array or arraylike
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against an asynchronous predicate, terminating on the first truthy
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value. If the predicate encounters an error, pass it to the completion
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callback. Otherwise, pass the truthy value passed by the predicate, or
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`false` if no truthy value was passed.
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Is
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[Zalgo](http://blog.izs.me/post/59142742143/designing-apis-for-asynchrony)-proof,
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browser-safe, and pretty efficient.
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## Usage
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```javascript
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var some = require("async-some");
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var resolve = require("path").resolve;
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var stat = require("fs").stat;
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var readFileSync = require("fs").readFileSync;
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some(["apple", "seaweed", "ham", "quince"], porkDetector, function (error, match) {
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if (error) return console.error(error);
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if (match) return console.dir(JSON.parse(readFileSync(match)));
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console.error("time to buy more Sporkle™!");
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});
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var PREFIX = resolve(__dirname, "../pork_store");
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function porkDetector(value, cb) {
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var path = resolve(PREFIX, value + ".json");
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stat(path, function (er, stat) {
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if (er) {
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if (er.code === "ENOENT") return cb(null, false);
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return cb(er);
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}
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cb(er, path);
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});
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}
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```
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### some(list, test, callback)
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* `list` {Object} An arraylike (either an Array or the arguments arraylike) to
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be checked.
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* `test` {Function} The predicate against which the elements of `list` will be
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tested. Takes two parameters:
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* `element` {any} The element of the list to be tested.
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* `callback` {Function} The continuation to be called once the test is
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complete. Takes (again) two values:
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* `error` {Error} Any errors that the predicate encountered.
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* `value` {any} A truthy value. A non-falsy result terminates checking the
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entire list.
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* `callback` {Function} The callback to invoke when either a value has been
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found or the entire input list has been processed with no result. Is invoked
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with the traditional two parameters:
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* `error` {Error} Errors that were encountered during the evaluation of some().
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* `match` {any} Value successfully matched by `test`, if any.
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