Javascript validation for .net dropdownlistbox control?

I have 3 dropdownlistbox..

1. country
2. state
3. cities

When I am selecting country name, as per its state name and city name change. In that if I am changing state name then city name is changed in dropdownlist box.

Using only Javascript not postback of .net control.

I have faced so much problem by making array of country, states and cities.

I thought if I have list of names of countries, states and cities than how can I maintain array of it?

So help me to get out of it, and give me good Javascript to get out from this problem?

Try this

var countries = [
   {
       name:'USA',
       states:[
            {
                name:'New York',
                cities:['New York','Albany',...,'Some place']
            },
            {
                name:'Florida',
                cities:['Miami','Ft Loterdale']
            }
       ]
   },
   {
        name:'Canada' ...
   }
]