Learning how to dynamically update a value in Angular based on user input

My goal is to dynamically change the output value based on user input using Angular. I have successfully implemented the functionality to increment the value, but unfortunately, when the input changes, the outputed value remains static.

Below is my current code snippet:

<input type="text" ng-change="myFunc()" ng-model="myValue" />
  <p>You have {{total}} points left.</p>
</div>

<script>
  angular.module('myApp', [])
    .controller('myCtrl', ['$scope', function($scope) {
      $scope.myValue = 0;      
      $scope.total = 5;
      $scope.myFunc = function() {
        $scope.total -= $scope.myValue;
      };
    }]);
</script>

I am looking for a solution where if the user clicks something like the backspace key, the total should revert back to its initial value of 5.

Any suggestions or ideas on how to achieve this?

Answer №1

In my opinion, the simpler approach would be

<input type="text" ng-model="myValue" />
<p>You have {{total - myValue}} points left.</p>
<button type="button" ng-click="myFunc()">

<script>
  angular.module('myApp', [])
    .controller('myCtrl', ['$scope', function($scope) {
        $scope.myValue = 0;      
        $scope.total = 5;

        $scope.myFunc = function() {
            $scope.total-=$scope.myValue;
        };
    }]);
</script>

This way, users can view the value but only make changes with a deliberate action

Answer №2

To return to the original value, you should validate the length of the input.

$scope.myFunc = function() {
    if(!$scope.myValue.length){
        $scope.total = 5; 
    }
    $scope.total-=$scope.myValue;
}

Explore this JSFiddle link for more details!

Answer №3

When updating your change function, consider starting with scope.initial instead of total. This way, you'll have a reference point to revert back to if the box is empty.

$scope.initial = 5;
$scope.myValue = 0;      
$scope.total = $scope.initial;

$scope.myFunc = function(){
  $scope.total = $scope.initial - myValue;
}

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