Adding a class to an element in AngularJS

Question

Adding a class to an element in AngularJS

I have a question about entering empty values in an input field and highlighting its boundary. I added a new class 'warning' for this purpose and created the following code.

HTML:

`<body ng-app="TestPage">
 <form ng-controller="TestForm">
  <input ng-model="testinput" class="form-input" ng-class="testclass" type="text"/>
  <button ng-click="submitButton()">Click</button>
</form>
</body>`

JavaScript:

`angular.module('TestPage',[])
    .controller('TestForm', function($scope, $animate) {
         $scope.submitButton = function() {
             if (($scope.testinput == undefined) || ($scope.testinput == "")) {
                 $animate.addClass($scope.testclass, "warning");
             }
         };
    });`

However, the addClass function does not seem to work as expected. What could be the issue here?

javascript angularjs

Answer 1

Answer №1

Per the documentation

The $animate service's addClass function requires three parameters:

The first parameter is the element to which the CSS classes will be applied.

The second parameter is the CSS class(es) that will be added (multiple classes separated by spaces).

The third parameter is an optional collection of options/styles to apply to the element.

To implement this, you can follow this example:

html:

`<body ng-app="TestPage">
 <form ng-controller="TestForm">
  <input id="target_element" ng-model="testinput" class="form-input" ng-class="testclass" type="text"/>
  <button ng-click="submitButton()">Click</button>
</form>
</body>`

Javascript:

`angular.module('TestPage',[])
    .controller('TestForm', function($scope, $animate){
        $scope.submitButton = function(){
            if (($scope.testinput == undefined) || ($scope.testinput == "")){
                $animate.addClass(angular.element('#target_element'), "warning");
            }
        };
    });`

A more effective approach is to use the directive.

module.directive('addClassBy',['$animate',function($animate){
    return function(scope,element){
        scope.$watch('testinput',function(newValue,oldValue){
            if(newValue === oldValue){return};
            if(newValue === undefined || newValue === ''){
                 $animate.addClass(element,'warning')
            }
        })
    }
}])

Then in HTML:

`<body ng-app="TestPage">
     <form ng-controller="TestForm">
      <input add-class-by ng-model="testinput" class="form-input" ng-class="testclass" type="text"/>
      <button ng-click="submitButton()">Click</button>
    </form>
    </body>`

Answer 2

Per the documentation

The $animate service's addClass function requires three parameters:

The first parameter is the element to which the CSS classes will be applied.

The second parameter is the CSS class(es) that will be added (multiple classes separated by spaces).

The third parameter is an optional collection of options/styles to apply to the element.

To implement this, you can follow this example:

html:

`<body ng-app="TestPage">
 <form ng-controller="TestForm">
  <input id="target_element" ng-model="testinput" class="form-input" ng-class="testclass" type="text"/>
  <button ng-click="submitButton()">Click</button>
</form>
</body>`

Javascript:

`angular.module('TestPage',[])
    .controller('TestForm', function($scope, $animate){
        $scope.submitButton = function(){
            if (($scope.testinput == undefined) || ($scope.testinput == "")){
                $animate.addClass(angular.element('#target_element'), "warning");
            }
        };
    });`

A more effective approach is to use the directive.

module.directive('addClassBy',['$animate',function($animate){
    return function(scope,element){
        scope.$watch('testinput',function(newValue,oldValue){
            if(newValue === oldValue){return};
            if(newValue === undefined || newValue === ''){
                 $animate.addClass(element,'warning')
            }
        })
    }
}])

Then in HTML:

`<body ng-app="TestPage">
     <form ng-controller="TestForm">
      <input add-class-by ng-model="testinput" class="form-input" ng-class="testclass" type="text"/>
      <button ng-click="submitButton()">Click</button>
    </form>
    </body>`

Adding a class to an element in AngularJS

Answer №1

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