import createTester from './internal/createTester.js' import eachOf from './eachOf.js' import awaitify from './internal/awaitify.js' /** * Returns the first value in `coll` that passes an async truth test. The * `iteratee` is applied in parallel, meaning the first iteratee to return * `true` will fire the detect `callback` with that result. That means the * result might not be the first item in the original `coll` (in terms of order) * that passes the test. * If order within the original `coll` is important, then look at * [`detectSeries`]{@link module:Collections.detectSeries}. * * @name detect * @static * @memberOf module:Collections * @method * @alias find * @category Collections * @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over. * @param {AsyncFunction} iteratee - A truth test to apply to each item in `coll`. * The iteratee must complete with a boolean value as its result. * Invoked with (item, callback). * @param {Function} [callback] - A callback which is called as soon as any * iteratee returns `true`, or after all the `iteratee` functions have finished. * Result will be the first item in the array that passes the truth test * (iteratee) or the value `undefined` if none passed. Invoked with * (err, result). * @returns {Promise} a promise, if a callback is omitted * @example * * // dir1 is a directory that contains file1.txt, file2.txt * // dir2 is a directory that contains file3.txt, file4.txt * // dir3 is a directory that contains file5.txt * * // asynchronous function that checks if a file exists * function fileExists(file, callback) { * fs.access(file, fs.constants.F_OK, (err) => { * callback(null, !err); * }); * } * * async.detect(['file3.txt','file2.txt','dir1/file1.txt'], fileExists, * function(err, result) { * console.log(result); * // dir1/file1.txt * // result now equals the first file in the list that exists * } *); * * // Using Promises * async.detect(['file3.txt','file2.txt','dir1/file1.txt'], fileExists) * .then(result => { * console.log(result); * // dir1/file1.txt * // result now equals the first file in the list that exists * }).catch(err => { * console.log(err); * }); * * // Using async/await * async () => { * try { * let result = await async.detect(['file3.txt','file2.txt','dir1/file1.txt'], fileExists); * console.log(result); * // dir1/file1.txt * // result now equals the file in the list that exists * } * catch (err) { * console.log(err); * } * } * */ function detect(coll, iteratee, callback) { return createTester(bool => bool, (res, item) => item)(eachOf, coll, iteratee, callback) } export default awaitify(detect, 3)