Semantic UI comes packaged with highly responsive components to cater to all front end needs. The area of front-end development is so large, it is never possible to cover all the possible requirements of a developer with pre built components. Currently there is no means to display notifications on the navbar in Open Event Front-end project. In this article we are going to build a notification dropdown from scratch which will be used there to display notifications. So we begin by generating a new component via ember CLI

$ ember generate component notification-dropdown

This should generate the boiler-plate code for our component, with the template file located at: templates/components/notification-dropdown.hbs and the JS file located at components/notification-dropdown.js  It is assumed that you already have a basic ember app with at least a navbar set up. The notification drop down will be integrated with the navbar as a separate component. This allows us great flexibility in terms of location of the navbar, and also helps us  in not cluttering the code in one file.

We will use the popup component of semantic ui as the underlying structure of our dropdown. I have used some dummy data stored in a separate file, you can use any dummy data you wish, either  by directly hardcoding it or importing it from a js file stored somewhere else. It’s preferred if the mock data is called from a js file, because it helps in simulating the server response in a much more genuine way.

We will make use of the floating label of semantic UI to display the number of unread notifications. A mail outline icon should make for a good choice to use the primary icon to denote the notifications. Also, the floating label will require additional styling to make it overlap with the icon perfectly.

For the header in the dropdown we can give a ‘mark all as read’ button aligned to the right and the ‘notification’ header to the left. Also for best user experience even on small devices, we will make each notification item clickable as a whole instead of individual clickable elements in it. A selection link list of semantic UI should be perfect to display individual notifications as it gives a hovering effect and also, allows us to display a header. Moving onto individual notification items, it will have 3 sub parts

• A header
• Description
• Human friendly notification time

For the header we will use the ‘header’ class predefined in semantic UI for list items.We will use ‘content’ class for description which is again a predefined semantic UI class, And finally the time can be displayed via moment-from-now helper of ember to display the time in a human friendly format.

<.i class="mail outline icon">
<./i>
<.div class="floating ui teal circular mini label">{{notifications.length}}<./div>
<.div class="ui wide notification popup bottom left transition ">
 <.div class="ui basic inverted horizontal segments">
   <.div class="ui basic left aligned segment weight-800">
     <.p>{{t 'Notifications'}}<./p>
   <./div>
   <.div class="ui basic right aligned segment weight-400">
     <.a href="#">{{t 'Mark all as Read'}}<./a>
   <./div>
 <./div>
 <.div class="ui fluid link celled selection list">
   {{#each notifications as |notification|}}
     <.div class="item">
       <.div class="header">
         {{notification.title}}
       <./div>
       <.div class="content weight-600">
         {{notification.description}}
       <./div>
       <.div class="left floated content">
         {{moment-from-now notification.createdAt}}
       <./div>
     <./div>
   {{/each}}
 <./div>
<./div>

Now the next challenge is to make the popup scrollable, they are not scrollable by default and may result in an error if their height exceeds that of the view port. So we apply some styling now. While applying such custom styles we have to be really careful so as to not to apply the styling in general to all of semantic UI’s components. It is very easy to overlook,  and may cause some unwanted changes. It is best to wrap it in a container class, in this case we have chosen to go ahead with notification as the class name. Also, since the notification dropdown should work consistently across all mobile devices, we need to set its maximum height not in terms of pixels but in terms of viewport height. The following styling code takes care of that as well as the icon which we are using to display the notification count.

.notification.item {
 margin: 0 !important;
 .label {
   top: 1em;
   padding: 0.2em;
   margin: 0 0 0 -3.2em !important;

 }
}

.ui.notification.popup {
 padding: 2px;
 .list {
   width: auto;
   max-height: 50vh;
   overflow: hidden;
   overflow-y: auto;
   padding: 0;
   margin: 0;
   .header {
     margin-bottom:5px;
   }
   .content {
     margin-bottom:2px;
   }
   }
 }

All of this takes care of the styling. Next, we need to take care of initialising the notification popup. For this we need to go to the navbar component as it is the one who calls the notification dropdown component. And add this to it:

didInsertElement() {
   this._super.call(this);
   this.$('.notification.item').popup({
     popup : '.popup',
     on    : 'click'
   });
 },

 willDestroyElement() {
   this._super.call(this);
   this.$('.notification.item').popup('destroy');
 }

The didInsertElement() makes sure that notification pop up is not rendered or initialised before the navbar is. On the other hand, willDestoroyElement() makes sure to clean up and destroy the pop up initialisation. Attached below are some screenshots of what the notification dropdown should look like.

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