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With Knockout, I can say
<html>
<head>
<script type="text/javascript" src="knockout-2.1.0.js"></script>
</head>
<body>
<input type="text" data-bind="value: a"></input> +
<input type="text" data-bind="value: b"></input> =
<span data-bind="text: result"></span>
<script type="text/javascript">
function ExampleViewModel() {
this.a = ko.observable(5);
this.b = ko.observable(6);
this.result = ko.computed(function() {
return parseInt(this.a()) + parseInt(this.b());
}, this);
}
ko.applyBindings(new ExampleViewModel());
</script>
</body>
</html>
and result will be recalculated every time a and b change. How can I get AngularJS to do this for me? I have tried
<html ng-app>
<head>
<script type="text/javascript" src="angular-1.0.1.min.js"></script>
<script type="text/javascript">
function ExampleCtrl($scope) {
$scope.a = 5;
$scope.b = 6;
$scope.result = function() {
return this.a + this.b
};
}
</script>
</head>
<body ng-controller="ExampleCtrl">
<input type="text" value="{{ a }}"></input> +
<input type="text" value="{{ b }}"></input> =
{{ result() }}
</body>
</html>
After a little more reading, I found ng-change:
<html ng-app>
<head>
<script type="text/javascript" src="angular-1.0.1.min.js"></script>
<script type="text/javascript">
function ExampleCtrl($scope) {
$scope.a = 5;
$scope.b = 6;
$scope.result = function() {
return parseInt($scope.a) + parseInt($scope.b)
};
}
</script>
</head>
<body ng-controller="ExampleCtrl">
<input type="text" ng-model="a" ng-change="result()"></input> +
<input type="text" ng-model="b" ng-change="result()"></input> =
{{ result() }}
</body>
</html>
But that requires me to keep track of the fact that changing a or b changes result(), is there any automatic way of detecting this?
346
Your result() function will be re-evaluated whenever the model changes when binding via ng-model in your inputs like this:
<input type="text" ng-model="a"></input>
instead of:
<input type="text" value="{{ a }}"></input>
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