each.js

import eachOf from './eachOf';
import withoutIndex from './internal/withoutIndex';
import wrapAsync from './internal/wrapAsync'
import awaitify from './internal/awaitify'

/**
 * Applies the function `iteratee` to each item in `coll`, in parallel.
 * The `iteratee` is called with an item from the list, and a callback for when
 * it has finished. If the `iteratee` passes an error to its `callback`, the
 * main `callback` (for the `each` function) is immediately called with the
 * error.
 *
 * Note, that since this function applies `iteratee` to each item in parallel,
 * there is no guarantee that the iteratee functions will complete in order.
 *
 * @name each
 * @static
 * @memberOf module:Collections
 * @method
 * @alias forEach
 * @category Collection
 * @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
 * @param {AsyncFunction} iteratee - An async function to apply to
 * each item in `coll`. Invoked with (item, callback).
 * The array index is not passed to the iteratee.
 * If you need the index, use `eachOf`.
 * @param {Function} [callback] - A callback which is called when all
 * `iteratee` functions have finished, or an error occurs. Invoked with (err).
 * @returns {Promise} a promise, if a callback is omitted
 * @example
 *
 * // assuming openFiles is an array of file names and saveFile is a function
 * // to save the modified contents of that file:
 *
 * async.each(openFiles, saveFile, function(err){
 *   // if any of the saves produced an error, err would equal that error
 * });
 *
 * // assuming openFiles is an array of file names
 * async.each(openFiles, function(file, callback) {
 *
 *     // Perform operation on file here.
 *     console.log('Processing file ' + file);
 *
 *     if( file.length > 32 ) {
 *       console.log('This file name is too long');
 *       callback('File name too long');
 *     } else {
 *       // Do work to process file here
 *       console.log('File processed');
 *       callback();
 *     }
 * }, function(err) {
 *     // if any of the file processing produced an error, err would equal that error
 *     if( err ) {
 *       // One of the iterations produced an error.
 *       // All processing will now stop.
 *       console.log('A file failed to process');
 *     } else {
 *       console.log('All files have been processed successfully');
 *     }
 * });
 */
function eachLimit(coll, iteratee, callback) {
    return eachOf(coll, withoutIndex(wrapAsync(iteratee)), callback);
}

export default awaitify(eachLimit, 3)