Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<div ng-controller="MyCtrl">
  Hello, {{name}}!
        <br/>
        <br/>
        <select id='clock' ng-model='clock' ng-options="clock as clock.clockName for clock in dropdowns"></select>
        <br/>
        <br/>
        <select id='freq' ng-model='freq' ng-disabled='!clock' ng-options="freq as freq.freq for freq in clock.freqs"></select>
        <br/>
        <br/>
        <select id='rate' ng-model='rate' ng-disabled='!clock || !freq' ng-options="rate as rate for rate in freq.rates"></select>
</div>

JavaScript

var myApp = angular.module('myApp',[]);

var dropdowns = [
    {
        clockName : "clock1",
        freqs : [
            { 
                freq : "freq1",
                rates : ["rate1", "rate2"]
            }, {
                freq : "freq2",
                rates : ["rate3", "rate4"]
            }
        ]
    }, {
        clockName : "clock2",
        freqs : [
            { 
                freq : "freq3",
                rates : ["rate5", "rate6"]
            }, {
                freq : "freq4",
                rates : ["rate7", "rate8"]
            }
        ]
    }
]
        

function MyCtrl($scope) {
    $scope.name = 'Superhero';
    $scope.dropdowns = dropdowns;
}