JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://code.angularjs.org/1.1.5/angular.js"></script>
<div ng-controller="selectCtrl" ng-app>
    Doesn't work when select's ngModel value is object:<br />
    <select ng-model="valueObject" ng-options="o.label for o in options"></select><br />
    <pre>{{valueObject | json}}</pre>
    
    Does work when select's ngModel value is object AND 'track by' expression is used:<br />
    <select ng-model="valueObject" ng-options="o.label for o in options track by o.value"></select><br />
    <pre>{{valueObject | json}}</pre>
</div>

JavaScript

function selectCtrl($scope) {    
    $scope.options = [
        {label: 'a', value: '1', someId: 333},
        {label: 'b', value: '2', someId: 555}
    ];    
    $scope.valueObject = {label: 'a', value: '1', someId: 333}; 
    $scope.$watch("valueObject", function(v){
    alert(JSON.stringify(v));
    })
};