Tips for ensuring a watcher only runs once in each digest cycle, regardless of how many times the property is modified

I am facing an issue with my function $scope.render() that relies on the value of $scope.myProperty to render a chart. Whenever myProperty changes during a digest cycle, I need to ensure that $scope.render() is called only once at the end of the digest cycle.

$scope.$watch('myProperty', function(v, vold) {
    if ($scope.switch) {
        $scope.myProperty ++;
        $scope.switch = false;
    }

    $scope.render();
});

The problem here is that if $scope.switch is true, then $scope.render() will be invoked twice within the same digest cycle. How can I make sure it's called only once?

javascriptangularjsangularjs-scope

Answer №1

The solution lies in utilizing Angular's convenient $timeout service.

var isChanged = false;
$scope.$watch('myData', function(newValue, oldValue) {
    if ($scope.flag) {
        $scope.myData ++;
        $scope.flag = false;
    }

    isChanged = true;

    $timeout(function() {
        if (isChanged) {
            $scope.updateView();
            isChanged = false;
        }
    });
});

With this implementation, the $scope.updateView function will execute every time there is a change in myData, ensuring it only happens once at the end of the digest cycle regardless of multiple changes to myData.

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