JavaScript: Convert all the items in object to lowercase

Hi,
I have an object in JavaScript whose values may be in UpperCase. I have a requirement where I need to convert all the values of the objects to lower case. Below is my code:

    <script type="text/javascript">
        var obj = { a: 'Hello', b: 'How', c: 'Are', d: 'You' };
        //obj.toLowerCase() ?    
    </script>

The output I need is:

var obj = { a: 'hello', b: 'how', c: 'are', d: 'you' };

    <script type="text/javascript">
        var obj = { a: 'Hello', b: 'How', c: 'Are', d: 'You' };
        for(var x in obj) {
            obj[x] = obj[x].toLowerCase();
        }
    </script>