Function _filter

deps/async.js:201–220

(eachfn, arr, iterator, callback)

    async.foldr = async.reduceRight;

    var _filter = function (eachfn, arr, iterator, callback) {
        var results = [];
        arr = _map(arr, function (x, i) {
            return {index: i, value: x};
        });
        eachfn(arr, function (x, callback) {
            iterator(x.value, function (v) {
                if (v) {
                    results.push(x);
                }
                callback();
            });
        }, function (err) {
            callback(_map(results.sort(function (a, b) {
                return a.index - b.index;
            }), function (x) {
                return x.value;
            }));
        });
    };
    async.filter = doParallel(_filter);
    async.filterSeries = doSeries(_filter);
    // select alias