detect.js

import identity from 'lodash/identity';

import createTester from './internal/createTester';
import doParallel from './internal/doParallel';
import findGetResult from './internal/findGetResult';

/**
 * 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|Object} coll - A collection to iterate over.
 * @param {Function} iteratee - A truth test to apply to each item in `coll`.
 * The iteratee is passed a `callback(err, truthValue)` which must be called
 * with a boolean argument once it has completed. 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).
 * @example
 *
 * async.detect(['file1','file2','file3'], function(filePath, callback) {
 *     fs.access(filePath, function(err) {
 *         callback(null, !err)
 *     });
 * }, function(err, result) {
 *     // result now equals the first file in the list that exists
 * });
 */
export default doParallel(createTester(identity, findGetResult));