Experiencing an issue where AngularJS $watch function is executing twice, making it difficult to compare old and new values for a

Question

Experiencing an issue where AngularJS $watch function is executing twice, making it difficult to compare old and new values for a

I'm working with AngularJS and I'm trying to monitor a variable for changes in order to decrease another variable. This is the code snippet I have so far:

$scope.$watch('watchMe', function () {
    $scope.decreaseMe--;
)

The watchMe variable is accessible across all scopes. I am using only one controller which handles both the function that modifies watchMe and the watch itself.

Each time watchMe changes, the watch function runs twice due to how Angular functions. However, this causes decreaseMe to be decremented twice as well, leading to an incorrect value.

I've attempted to compare old and new values but haven't been successful in resolving the issue.

When watchMe changes once, these are the values I observe for old/new/decreased:

old: 7  new: 8 
decreasing  5
old: 7  new: 8 
decreasing  4

How can I adjust my code to ensure decreaseMe is decreased only once when watchMe changes?

Update:

I tried creating a Plunkr example to demonstrate this problem but the $watch function in Plunkr only triggers once.

javascript angularjs angularjs-scope watch

Answer 1

Answer №1

Is this function not operational?

$scope.$watch('watchMe', function( updatedVal, pastVal ) {
    if( updatedVal != pastVal ) {
        $scope.decreaseMe--;
    }
});

Answer 2

Is this function not operational?

$scope.$watch('watchMe', function( updatedVal, pastVal ) {
    if( updatedVal != pastVal ) {
        $scope.decreaseMe--;
    }
});

Answer 3

Answer №2

To get a better understanding of your setup, it would be helpful if you could provide more code samples. From my experience, I encountered a similar issue in the past when I accidentally included the AngularJS library twice on the same page.

Answer 4

To get a better understanding of your setup, it would be helpful if you could provide more code samples. From my experience, I encountered a similar issue in the past when I accidentally included the AngularJS library twice on the same page.

Answer 5

Answer №3

Encountering a similar issue arose for me while utilizing directive templates alongside a shared controller. This resulted in the controller code executing twice.

(To confirm this, try logging to the console outside of your watch statement - you'll likely observe a duplicate entry)

.directive('directiveOne', function () {
    return {
        templateUrl: 'app/templates/directive-one.html',
        restrict: 'A',
        controller: 'directiveController'
    };
})
.directive('directiveTwo', function() {
    return {
        templateUrl: 'app/templates/directive-two.html',
        restrict: 'A',
        controller: 'directiveController'
    };
})

The resolution I found was to segregate them into their individual controllers

For instance:

.directive('directiveOne', function () {
    return {
        templateUrl: 'app/templates/directive-one.html',
        restrict: 'A',
        controller: 'directiveOneController'
    };
})
.directive('directiveTwo', function() {
    return {
        templateUrl: 'app/templates/directive-two.html',
        restrict: 'A',
        controller: 'directiveTwoController'
    };
})

Answer 6

Encountering a similar issue arose for me while utilizing directive templates alongside a shared controller. This resulted in the controller code executing twice.

(To confirm this, try logging to the console outside of your watch statement - you'll likely observe a duplicate entry)

.directive('directiveOne', function () {
    return {
        templateUrl: 'app/templates/directive-one.html',
        restrict: 'A',
        controller: 'directiveController'
    };
})
.directive('directiveTwo', function() {
    return {
        templateUrl: 'app/templates/directive-two.html',
        restrict: 'A',
        controller: 'directiveController'
    };
})

The resolution I found was to segregate them into their individual controllers

For instance:

.directive('directiveOne', function () {
    return {
        templateUrl: 'app/templates/directive-one.html',
        restrict: 'A',
        controller: 'directiveOneController'
    };
})
.directive('directiveTwo', function() {
    return {
        templateUrl: 'app/templates/directive-two.html',
        restrict: 'A',
        controller: 'directiveTwoController'
    };
})

Experiencing an issue where AngularJS $watch function is executing twice, making it difficult to compare old and new values for a

I tried creating a Plunkr example to demonstrate this problem but the $watch function in Plunkr only triggers once.

Answer №1

Answer №2

Answer №3

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