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lib\collector.class.js (2773, 2022-11-15)
lib\collector.functor.js (2139, 2022-11-15)
lib\collector.js (3531, 2022-11-15)
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lib\memoize.js (2112, 2022-11-15)
lib\poolify.js (1064, 2022-11-15)
lib\poolify.opt.js (1025, 2022-11-15)
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# Asynchronous Programming Library [](https://github.com/metarhia/metasync/actions?query=workflow%3A%22Testing+CI%22+branch%3Amaster) [](https://snyk.io/test/github/metarhia/metasync) [](https://badge.fury.io/js/metasync) [](https://www.npmjs.com/package/metasync) [](https://www.npmjs.com/package/metasync) [](https://github.com/metarhia/metasync/blob/master/LICENSE) ## Installation ```bash $ npm install metasync ``` ## Asynchronous functions composition `metasync(fns)(data, done)` - `fns` - array of callback-last functions, callback contranct err-first - `data` - input data (optional) - `done` - err-first callback - Returns: composed callback-last / err-first function  ```js const composed = metasync([f1, f2, f3, [[f4, f5, [f6, f7], f8]], f9]); ``` - Array of functions gives sequential execution: `[f1, f2, f3]` - Double brackets array of functions gives parallel execution: `[[f1, f2, f3]]` _Example:_ ```js const metasync = require('metasync'); const fs = require('fs'); // Data collector (collect keys by count) const dc = metasync.collect(4); dc.pick('user', { name: 'Marcus Aurelius' }); fs.readFile('HISTORY.md', (err, data) => dc.collect('history', err, data)); dc.take('readme', fs.readFile, 'README.md'); setTimeout(() => dc.pick('timer', { date: new Date() }), 1000); // Key collector (collect certain keys by names) const kc = metasync .collect(['user', 'history', 'readme', 'timer']) .timeout(2000) .distinct() .done((err, data) => console.log(data)); kc.pick('user', { name: 'Marcus Aurelius' }); kc.take('history', fs.readFile, 'HISTORY.md'); kc.take('readme', fs.readFile, 'README.md'); setTimeout(() => kc.pick('timer', { date: new Date() }), 1000); ``` ## API ### callbackify(fn) - `fn`: [``][function] promise-returning function _Returns:_ [``][function] Convert Promise-returning to callback-last / error-first contract ### asyncify(fn) - `fn`: [``][function] regular synchronous function _Returns:_ [``][function] with contract: callback-last / error-first Convert sync function to callback-last / error-first contract ### promiseToCallbackLast(promise, callback) - `promise`: [``][promise] - `callback`: [``][function] Convert Promise to callback-last ### promisify(fn) - `fn`: [``][function] callback-last function _Returns:_ [``][function] Promise-returning function Convert async function to Promise-returning function ### promisifySync(fn) - `fn`: [``][function] regular synchronous function _Returns:_ [``][function] Promise-returning function Convert sync function to Promise object ### map(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] to be executed for each value in the array - `current`: `` current element being processed in the array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `value`: `` - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: [``][array] Asynchronous map (iterate parallel) ### filter(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] to be executed for each value in the array - `value`: `` item from items array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `accepted`: [``][boolean] - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: [``][array] Asynchrous filter (iterate parallel) _Example:_ ```js metasync.filter( ['data', 'to', 'filter'], (item, callback) => callback(item.length > 2), (err, result) => console.dir(result), ); ``` ### reduce(items, fn, done\[, initial\]) - `items`: [``][array] incoming - `fn`: [``][function] to be executed for each value in array - `previous`: `` value previously returned in the last iteration - `current`: `` current element being processed in the array - `callback`: [``][function] callback for returning value back to reduce function - `err`: [``][error]|[``][null] - `data`: `` resulting value - `counter`: [``][number] index of the current element being processed in array - `items`: [``][array] the array reduce was called upon - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: [``][array] - `initial`: `` optional value to be used as first argument in first iteration Asynchronous reduce ### reduceRight(items, fn, done\[, initial\]) - `items`: [``][array] incoming - `fn`: [``][function] to be executed for each value in array - `previous`: `` value previously returned in the last iteration - `current`: `` current element being processed in the array - `callback`: [``][function] callback for returning value back to reduce function - `err`: [``][error]|[``][null] - `data`: `` resulting value - `counter`: [``][number] index of the current element being processed in array - `items`: [``][array] the array reduce was called upon - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: [``][array] - `initial`: `` optional value to be used as first argument in first iteration Asynchronous reduceRight ### each(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] - `value`: `` item from items array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `items`: [``][array] Asynchronous each (iterate in parallel) _Example:_ ```js metasync.each( ['a', 'b', 'c'], (item, callback) => { console.dir({ each: item }); callback(); }, (err, data) => console.dir('each done'), ); ``` ### series(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] - `value`: `` item from items array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `items`: [``][array] Asynchronous series _Example:_ ```js metasync.series( ['a', 'b', 'c'], (item, callback) => { console.dir({ series: item }); callback(); }, (err, data) => { console.dir('series done'); }, ); ``` ### find(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] - `value`: `` item from items array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `accepted`: [``][boolean] - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: `` Asynchronous find (iterate in series) _Example:_ ```js metasync.find( [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16], (item, callback) => callback(null, item % 3 === 0 && item % 5 === 0), (err, result) => { console.dir(result); }, ); ``` ### every(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] - `value`: `` item from items array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `accepted`: [``][boolean] - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: [``][boolean] Asynchronous every ### some(items, fn, done) - `items`: [``][array] incoming - `fn`: [``][function] - `value`: `` item from items array - `callback`: [``][function] - `err`: [``][error]|[``][null] - `accepted`: [``][boolean] - `done`: [``][function] on done - `err`: [``][error]|[``][null] - `result`: [``][boolean] Asynchronous some (iterate in series) ### asyncMap(items, fn\[, options\]\[, done\]) - `items`: [``][array] incoming dataset - `fn`: [``][function] - `item`: `` - `index`: [``][number] - `options`: [`