Adding class to element using Angular JS

AngularJS has some methods called JQlite so we can use it. see link

Select the element in DOM is

angular.element( document.querySelector( '#div1' ) );

add the class like .addClass('alpha');

So finally

var myEl = angular.element( document.querySelector( '#div1' ) );
myEl.addClass('alpha');

You can use ng-class to add conditional classes.

HTML

<button id="button1" ng-click="alpha = true" ng-class="{alpha: alpha}">Button</button>

In your controller (to make sure the class is not shown by default)

$scope.alpha = false;

Now, when you click the button, the $scope.alpha variable is updated and ng-class will add the 'alpha' class to your button.

Try this..

If jQuery is available, angular.element is an alias for the jQuery function.

var app = angular.module('myApp',[]);

app.controller('Ctrl', function($scope) {

    $scope.click=function(){

      angular.element('#div1').addClass("alpha");
    };
});
<div id='div1'>Text</div>
<button ng-click="click()">action</button>

Ref:https://docs.angularjs.org/api/ng/function/angular.element

Use the MV* Pattern

Based on the example you attached, It's better in angular to use the following tools:

• ng-click - evaluates the expression when the element is clicked (Read More)
• ng-class - place a class based on the a given boolean expression (Read More)

for example:

<button ng-click="enabled=true">Click Me!</button>

<div ng-class="{'alpha':enabled}"> 
    ...
</div>

This gives you an easy way to decouple your implementation. e.g. you don't have any dependency between the div and the button.

Read this to learn about the MV* Pattern

First thing, you should not do any DOM manipulation in controller function. Instead, you should use directives for this purpose. directive's link function is available for those kind of stuff only.

AngularJS Docs : Creating a Directive that Manipulates the DOM

app.directive('buttonDirective', function($timeout) {
  return {
    scope: {
       change: '&'
    },
    link: function(scope, element, attrs) {
      element.bind('click', function() {
        $timeout(function() {
          // triggering callback
          scope.change();
        });
      });
    }
  };
});

change callback can be used as listener for click event.