extend deep ,

gistfile1.js

function type(source) {
    return Object.prototype.toString.call(source).replace(/^\[object (.+)\]/g, '$1').toLowerCase();
}
function forEach(source, callback) {
    var type = type(source)
    if (type === 'array')
        for (var i = 0, l = source.length;i < l;i++) {
            callback(source[i], i);
        }
    }
    else if (type === 'object') {
        for (var k in source) {
            source.hasOwnProperty(k) && callback(source[k], k);            
        }
    } else {
        return undefined;
    }
}
function extend() {
    var args = Array.prototype.slice.call(arguments),
        result = args.shift(),
        source = args.shift();
    forEach(source, function(v, k) {
        //console.log(k);
        if (type(v) === 'object') {
            result[k] = result[k] || {};
            extend.call(this, result[k], v);
        } else {
            result[k] = v;
        }
    });
    return args.length > 0 ? extend.apply(this, (args.unshift(result), args)) : result;
}