Angular $watch problem

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I am learning Angular. Please tell me why the $watch at the very bottom does not work:

HTML

<html>
<head>
	<link rel="Stylesheet" href="c.css" type="text/css" />
</head>
<body ng-app ng-controller='StudentListController'>
	<ul >
		<li ng-repeat='student in students'>
			<a href='/student/view/{{student.id}}' class="menu-{{student.valid}}">{{student.name}}</a>
			<input type="text" ng-model="student.quantity" />
		</li>
	</ul>
	<button ng-click="Sum()" class="menu-true">Sum</button>
	<div>{{sum}}</div>
</body>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.1/angular.min.js"></script>
<script>
	var students = [{ name: 'Mary Contrary', id: '1', valid: 'true', quantity: 0 },
{ name: 'Jack Sprat', id: '2', valid: 'false', quantity: 0 },
{ name: 'Jill Hill', id: '3', valid: 'false', quantity: 0 }];

	function StudentListController($scope)
	{
		$scope.students = students;
		$scope.sum = 0;

		$scope.Sum = function ()
		{
			$scope.sum = 0;
			for (var i = 0;  i < $scope.students.length; i++)
			{
				$scope.sum = parseFloat($scope.sum) + parseFloat($scope.students[i].quantity);
			}
		};

		$scope.$watch($scope.students[1], $scope.Sum, 'true');
	}

</script>
</html>

Posted 2-Apr-14 21:29pm

Yoyosch

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Comments

Richard MacCutchan 3-Apr-14 4:25am

What do you mean by "does not work"?

1 solution

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Vindhyachal_Kumar · Answer 1 · 2014-08-03T20:06:00

You can use this alternative code

XML

<html>
<body ng-app ng-controller='StudentListController'>
    <ul>
        <li ng-repeat='student in students'><a href='/student/view/{{student.id}}' class="menu-{{student.valid}}">
            {{student.name}} </a>
            <input ng-model="student.quantity" ng-change='Sum()' />
        </li>
    </ul>
    <button ng-click="Sum()" class="menu-true">
        Sum</button>
    <div>
        {{sum}}</div>
</body>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/angularjs/1.2.21/angular.min.js"></script>
<script type="text/javascript">
    var students = [{ name: 'Mary Contrary', id: '1', valid: 'true', quantity: 0 },
{ name: 'Jack Sprat', id: '2', valid: 'false', quantity: 0 },
{ name: 'Jill Hill', id: '3', valid: 'false', quantity: 0}];

    function StudentListController($scope) {
        $scope.students = students;
        $scope.sum = 0;

        $scope.Sum = function () {
            $scope.sum = 0;
            for (var i = 0; i < $scope.students.length; i++) {
                $scope.sum = parseFloat($scope.sum) + parseFloat($scope.students[i].quantity);
            }
        };

    }

</script>
</html>