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import isArrayLike from 'lodash/isArrayLike';
import eachOfLimit from './eachOfLimit';
import doLimit from './internal/doLimit';
import noop from 'lodash/noop';
import once from 'lodash/once';
import onlyOnce from './internal/onlyOnce';
// eachOf implementation optimized for array-likes
function eachOfArrayLike(coll, iteratee, callback) {
callback = once(callback || noop);
var index = 0,
completed = 0,
length = coll.length;
if (length === 0) {
callback(null);
}
function iteratorCallback(err) {
if (err) {
callback(err);
} else if (++completed === length) {
callback(null);
}
}
for (; index < length; index++) {
iteratee(coll[index], index, onlyOnce(iteratorCallback));
}
}
// a generic version of eachOf which can handle array, object, and iterator cases.
var eachOfGeneric = doLimit(eachOfLimit, Infinity);
/**
* Like [`each`]{@link module:Collections.each}, except that it passes the key (or index) as the second argument
* to the iteratee.
*
* @name eachOf
* @static
* @memberOf module:Collections
* @method
* @alias forEachOf
* @category Collection
* @see [async.each]{@link module:Collections.each}
* @param {Array|Iterable|Object} coll - A collection to iterate over.
* @param {Function} iteratee - A function to apply to each
* item in `coll`. The `key` is the item's key, or index in the case of an
* array. The iteratee is passed a `callback(err)` which must be called once it
* has completed. If no error has occurred, the callback should be run without
* arguments or with an explicit `null` argument. Invoked with
* (item, key, callback).
* @param {Function} [callback] - A callback which is called when all
* `iteratee` functions have finished, or an error occurs. Invoked with (err).
* @example
*
* var obj = {dev: "/dev.json", test: "/test.json", prod: "/prod.json"};
* var configs = {};
*
* async.forEachOf(obj, function (value, key, callback) {
* fs.readFile(__dirname + value, "utf8", function (err, data) {
* if (err) return callback(err);
* try {
* configs[key] = JSON.parse(data);
* } catch (e) {
* return callback(e);
* }
* callback();
* });
* }, function (err) {
* if (err) console.error(err.message);
* // configs is now a map of JSON data
* doSomethingWith(configs);
* });
*/
export default function(coll, iteratee, callback) {
var eachOfImplementation = isArrayLike(coll) ? eachOfArrayLike : eachOfGeneric;
eachOfImplementation(coll, iteratee, callback);
}
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