Asynchronous forEach function

forEach

function forEach(list, fn, done, options) {

    if (typeof fn !== 'function') {
        throw new Error('Second param expected type "function"');
    }

    var fnDesc = fn.toString();
    var next;
    var len = list.length;
    var index = 0;
    var returnVal;
    
    options = options || {};

    var iterate = function () {
        if (index < len) {
            returnVal = fn(list[index], next);
            if (returnVal !== undefined) {
                iterate = null;
                return done(returnVal);
            }
            index += 1;
            if (!next) {
                iterate();
            }
        } else if (typeof done === 'function') {
            iterate = null;
            done();
        }
    };

    var argsContainer = fnDesc.match(/\(.*?\)\s?\{/gm);
    if (argsContainer[0].match(/\bnext\b/gm)) {
        next = function () {
            setTimeout(iterate, options.delay);
        };
    }

    iterate();
}

// :: Usage :: //
var arr = [1, 2, 3];
forEach(arr, function(item, next) {
    console.log('foreach item', item);
next();
}, function(){
    console.log('we are done')
}, {
 delay: 1000
});