Using Ember.js Components in Open Event Frontend

Ember.js is a comprehensive JavaScript framework for building highly ambitious web applications. The basic tenet of Ember.js is convention over configuration which means that it understands that a large part of the code, as well as development process, is common to most of the web applications. Talking about the components which are nothing but the elements whose role remain same with same properties and functions within the entire project. Components allow developers to bundle up HTML elements and styles into reusable custom elements which can be called anywhere within the project.

In Ember, the components consist of two parts: some JavaScript code and an HTMLBars template. The JavaScript component file defines the behaviour and properties of the component. The behaviours of the component are typically defined using actions. The HTMLBars file defines the markup for the component’s UI. By default, the component will be rendered into a ‘div’ tag element, but a different element can be defined if required. A great thing about templates in Ember is that other components can be called inside of a component’s template. To call a component in an Ember app, we must use {{curly-brace-syntax}}. By design, components are completely isolated which means that they are not directly affected by any surrounding CSS or JavaScript.

Let’s demonstrate a basic Ember component in reference to Open Event Frontend Project for displaying the text as a popup. The component will render a simple text view which will display the entire text. The component is designed with the purpose that many times due to unavailability of space we’re unable to show the complete text so such cases the component will compare the available space with the space required by the whole text view to display the text. If in case the available space is not sufficient then the text will be ellipsized and on hovering the text a popup will appear where the complete text can be seen.

Generating the component

The component can be generated using the following command:

$ ember g component smart-overflow

Note: The components name needs to include a hyphen. This is an Ember convention, but it is an important one as it’ll ensure there are no naming collisions with future HTML elements.This will create the required .js and .hbs files needed to define the component, as well as an Ember integration test.

The Component Template

In the app/templates/components/smart-overflow.hbs file we can create some basic markup to display the text when the component is called.

<span> {{yield}} </span>

The {{yield}} is handlebars expressions which will be helpful in rendering the data to display when the component is called.

The JavaScript Code

In the app/components/smart-overflow.js file, we will define the how the component will work when it is called.

import Ember from 'ember';

const { Component } = Ember;

export default Component.extend({
  classNames: ['smart-overflow'],
  didInsertElement() {
    var $headerSpan = this.$('span');
    var $header = this.$();
    $header.attr('data-content', $headerSpan.text());
    $header.attr('data-variation', 'tiny');
    while ($headerSpan.outerHeight() > $header.height()) {
      $headerSpan.text((index, text) => {
        return text.replace(/\W*\s(\S)*$/, '...');
        position: 'top center'
      this.set('$header', $header);
  willDestroyElement() {
    if (this.get('$header')) {


In the above piece of code, we have first taken the size of the available space in header variable and then taken the size of the content in header span variable. After that, we’re comparing both the sizes to check if the content is greater than the available space then we are ellipsizing the content and create a popup to display the complete text to produce good user experience.

Passing data to the component

To allow the component to display the data properly, we need to pass it in.

In the app/templates/components/event-card.hbs file we can call the component as many times as desired and pass in relevant data for each attribute.

<div class="ui card {{unless isWide 'event fluid' 'thirteen wide computer ten wide tablet sixteen wide mobile column'}}">
    {{#unless isWide}}
      <a class="image" href="{{href-to 'public' event.identifier}}">
        {{widgets/safe-image src=(if event.large event.large event.placeholderUrl)}}
    <a class="main content" href="{{href-to 'public' event.identifier}}">
      {{#smart-overflow class='header'}}
      <div class="meta">
        <span class="date">
          {{moment-format event.startTime 'ddd, MMM DD HH:mm A'}}
      {{#smart-overflow class='description'}}
    <div class="extra content small text">
      <span class="right floated">
        <i role="button" class="share alternate link icon" {{action shareEvent event}}></i>
        {{#if hasBlock}}
          {{#each tags as |tag|}}


Now if you view the app in the browser at localhost:4200, you will see something like this.

Fig. 1

In the end, we can say that with the components, the code remains much clear and readable. It makes more sense to the developers who happen upon them. The best part about them is their reusability across the application making the development process faster and much more efficient.

Reference: The Complete source for the smart overflow can be found here.

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