Рекурсивное объединение объектов

_extend.js

function _extend(to, from) {
    var i;
    var toStr = Object.prototype.toString;
    var astr = '[object Array]';
    to = to || {};

    for (i in from) {
        if (from.hasOwnProperty(i)) {
            if (typeof from[i] === 'object') {
                to[i] = (toStr.call(from[i]) === astr) ? [] : {};
                namespace.ya.speechkit._extend(to[i], from[i]);
            } else if (typeof from[i] !== 'undefined' || typeof to[i] === 'undefined') {
                to[i] = from[i];
            }
        }
    }
    return to;
};