Filtered look-up using javascript or jquery

Question

I have a webpage that has 3 drop down fields.

Country

State

City

I need to apply filtered look-up for State (based on country) and city (based on state).

I want to achieve using Javascript or Jquery.

PS : The website is not based on any Microsoft technologies or PHP.

Update: I have tried various examples listed below but I am not getting closer to filtered lookup.

a) http://forum.jquery.com/topic/set-dropdown-list-selected-value-after-dynamically-populating

b) http://www.mkyong.com/jquery/how-to-set-a-dropdown-box-value-in-jquery/

c) How do you select a particular option in a SELECT element in jQuery?

Update2

<form method="post">States:
<select name="Select1">
    <option>NJ</option>
    <option>NY</option>
    <option>PA</option>
    <option>TX</option>
</select>

<form method="post">City List:
<select name="Select2">
    <option>Trenton</option>
    <option>Albany</option>
    <option>Philly</option>
    <option>Newark</option>
    <option>NYC</option>
    <option>Pittsburgh</option>
    <option>Hackensack</option>
    <option>Niagara</option>
    <option>Harrisburg</option>
</select>

$(function () { var $States = $('select[name=Select1]'); var $Cities = $('select[name=Select2]');

var $citiesList = $Cities.find('option').clone();

var workerandFruits = {
    NJ: ["Trenton", "Newark", "Hackensack"],
    NY: ["Albany", "NYC", "Niagara"],        
    PA: ["Philly", "Pittsburgh", "Harrisburg"]
}

$States.change(function () {
    var $selectedWorker = $(this).find('option:selected').text();
    $Cities.html($citiesList.filter(function () {
         return $.inArray($(this).text(), workerandFruits[$selectedWorker]) >= 0;
    }));
});

});

Answer 1

Ok, let's start with this:

$(function () {
    var citiesByState = {
        NJ: ["Trenton", "Newark", "Hackensack"],
        NY: ["Albany", "NYC", "Niagara"],
        PA: ["Philly", "Pittsburgh", "Harrisburg"]
    }

    $('select[name=state]').change(function () {
        var cities = citiesByState[$(this).val()];
        var opts = $.map(cities, function(name) {
            return "<option>" + name + "</option>";
        });
        $('select[name=city]').html(opts.join(""));
    });
});

http://jsfiddle.net/d8hY5/1/

Let us know if you have questions.