Adding tip to drop downs in Susper using CSS in Angular

To create simple drop downs using twitter bootstrap, it is fairly easy for developers. The issue faced in Susper, however, was to add a tip on the top over such dropdowns similar to Google:

This is how it looks finally, in Susper, with a tip over the standard rectangular drop-down:

This is how it was done:

  1. First, make sure you have designed your drop-down according to your requirements, added the desired height, width and padding. These were the specifications used in Susper’s drop-down.

height: 500px;
width: 327px;
padding: 28px;
  1. Next add the following code to your drop-down class css:

.dropdown-menu:before {
position: absolute;
top: -7px;
right: 19px;
display: inlineblock;
border-right: 7px solid transparent;
border-bottom: 7px solid #ccc;
border-left: 7px solid transparent;
border-bottom-color: rgba(0, 0, 0, 0.2);
content: ;
.dropdown-menu:after {
position: absolute;
top: -5px;
right: 20px;
display: inlineblock;
border-right: 6px solid transparent;
border-bottom: 6px solid #ffffff;
border-left: 6px solid transparent;
content: ;

In css, :before inserts the style before any other html, whereas :after inserts the style after the html is loaded. Some of the parameters are explained here:

  • Top: can be used to change the position of the menu tip vertically, according to the position of your button and menu.
  • Right: can be used to change the position of the menu tip horizontally, so that it can be positioned used below the menu icon.
  • Position : absolute is used to make sure all our values are absolute and not relative to the higher div hierarchically
  • Border: All border attributes are used to specify border thickness, color and transparency before and after, which collectively gives the effect of a tip for the drop down.
  • Content : This value is set to a blank string ‘’, because otherwise none of our changes will be visible, since the divs will have no space allocated to them.


Using Hidden Attribute for Angular in Susper

In Angular, we can use the hidden attribute, to hide and show different components of the page. This blog explains what the hidden attribute is, how it works and how to use it for some common tasks.
In Susper, we used the [hidden] attribute for two kinds of tasks.

  1. To hide components of the page until all the search results load.
  2. To hide components of the page, if they were meant to appear only in particular cases (say only the first page of the search results etc).

Let us now see how we apply this in a html file.
Use the [hidden] attribute for the component, to specify a flag variable responsible for hiding it.
When this variable is set to true or 1, the component is hidden otherwise it is shown.
Here is an example of how the [hidden] attribute is used:

<app-infobox [hidden]=”hidefooter class=“infobox col-md-4” *ngIf=“Display(‘all’)”></app-infobox>

Note that [hidden] in a way simply sets the css of the component as { display: none }, whereas in *ngIf, the component is not loaded in the DOM.
So, in this case unless Display(‘all’) returns true the component is not even loaded to the DOM but if [hidden] is set to true, then the component is still present, only not displayed.
In the typescript files, here is how the two tasks are performed:
To hide components of the page, until all the search results load.

this.querychange$ =;
this.querychange$.subscribe(res => {
this.hidefooter = 1;

this.responseTime$ =;
this.responseTime$.subscribe(responsetime => {
this.hidefooter = 0;

The component is hidden when the query request is just sent. It is then kept hidden until the results for the previously sent query are available.

2. To hide components of the page, if they were meant to appear only in particular cases.
For example, if you wish to show a component like Autocorrect only when you are on the first page of the search results, here is how you can do it:

if (this.presentPage === 1) {
this.hideAutoCorrect = 0;
} else {
this.hideAutoCorrect = 1;

This should hopefully give you a good idea on how to use the hidden attribute. These resources can be referred to for more information.

Implementing a suggestion box in Susper Angular JS Front-end

In Susper, we have implemented a suggestion box for our input box. This was done using Yacy suggest API. This is how the box looks:

In this blog, let us see how to implement such a box using html, css, twitter-bootstrap and typescript. You can also check the code at the Susper repository.

The html code is simple and straightforward:


class=“suggestion-box” *ngIf=“results”>


A few points to notice :

  • *ngIf=”results” ensures that the box is displayed only when it has suggestions to display and not otherwise
  • The [routerLink] and [queryParams] attributes together link every result to the search page, with the correct query.

This is the css code :

a {
text-decoration: none;
}.suggestions {
font-family: Arial, sans-serif;
font-size: 17px;
margin-left: 2.4%;
}.query-suggestions:hover {
background: #E3E3E3;
width: 635.2px;
max-width: 100%;
border: 1px solid rgba(150,150,150,0.3);
background-color: white;
margin-left: -25.7px;
position: absolute;
boxshadow: 0px 0.2px 0px;

A few points to notice again:

    • Box-shadow: This gives the drop up a shadow effect, which looks really nice, the first 3 parameters are for dimensions (X-offset, Y-offset, Blur). The rgba specifies color, with parameters as (red-component, green-component, blue-component, opacity).
    • Text-decoration: This attribute is used to add/remove decoration like underline for links.
    • Font-family: The font-family mentioned here is Arial, if Arial is unavailable sans-serif is used.

In the typescript file, there are two major tasks:

  1. Splice the results if greater than five. A neat suggestion-box should have a maximum of five results, hence we splice the results:

if ( this.results.length > 5) {
this.results = this.results.splice (0, 5);
  1. Hide the suggestion-box if there are no suggestions from the API:
@Output() hidecomponent: EventEmitter<any> = new EventEmitter<any>();

this.query$.subscribe( query => {
if (query) {
this.autocompleteservice.getsearchresults(query).subscribe(res => {
if (res) {
this.results = res[1];
if (this.results.length === 0) {
} else {

If you want a more elaborate picture, you can view the entire html, css and typescript files of the auto-complete component.

This tutorial, is very useful in case you want to implement auto complete suggestion feature from scratch.

In addition, this stack overflow thread has some interesting insights too:

Implementing Themes in Angular JS for Susper

Adding themes to any website, makes it more interesting to use, and also helps customize the website according to personal preferences. This blog deals with how we implemented themes in Susper.
Susper offers the following themes

  • Default
  • Dark
  • Basic
  • Contrast
  • Terminal

This is how some of the themes look

Lets go through a step by step guide how to implement this:

  1. Add a Themes service  (In app/src/theme.service.ts in Susper)

Here is the code snippet:

import { Injectable } from ‘@angular/core’;

export class ThemeService {

public titleColor: string;
public linkColor: string;
public descriptionColor: string;
public backgroundColor: string;

constructor() { }


  1.  Create a component for themes, and define functions for various themes in the .ts file.(src/app/theme/theme.component.ts in Susper)

Here is the example code:

import { Component, OnInit } from ‘@angular/core’;
import { ThemeService } from ‘../theme.service’;@Component({
selector: ‘app-theme’,
templateUrl: ‘./theme.component.html’,
styleUrls: [‘./theme.component.css’]
export class ThemeComponent implements OnInit {constructor(
private themeService: ThemeService
) { }ngOnInit() {
}darkTheme() {
this.themeService.backgroundColor = ‘#FFFFFF’;
this.themeService.titleColor = ‘#050404’;
this.themeService.linkColor = ‘#7E716E’;
this.themeService.descriptionColor = ‘#494443’;

defaultTheme() {
this.themeService.backgroundColor = ‘#FFFFFF’;
this.themeService.titleColor = ‘#1a0dab’;
this.themeService.linkColor = ‘#006621’;
this.themeService.descriptionColor = ‘#545454’;

basicTheme() {
this.themeService.backgroundColor = ‘#FFFFFF’;
this.themeService.titleColor = ‘#1a0dab’;
this.themeService.linkColor = ‘#494443’;
this.themeService.descriptionColor = ‘#7E716E’;

In the above code, the first few lines  include the constructor, which defines the theme service, and include a default function that runs as soon as the page is initialized.

We then see three kinds of themes implemented, dark, default and contrast. Let us examine the darkTheme:

darkTheme() {
this.themeService.backgroundColor = ‘#FFFFFF’;
this.themeService.titleColor = ‘#050404’;
this.themeService.linkColor = ‘#7E716E’;
this.themeService.descriptionColor = ‘#494443’;
  • The first line sets the background color of the screen(to white).
  • The second line is used to set the color of all the titles of the search results
  • The third line is used to set the link/url color
  • The fourth line sets the description color
    1.   Link the appropriate attributes in your html pages, using [style.’css-attribute’]

(src/app/results/results.component.html in Susper)

Following this example, you can link different parts of the html file to the attributes in your theme service and you are done!
If implementing this in a project like Susper, a few points of caution:

  • Make sure you write your spec.ts file well, and add your component for proper compilation and testing.
  • Do not forget to import the service into any component before you use it in its html files.


Implementing a Pagination Bar in Susper Angular JS Frontend

Searching on Susper most queries will have a number of search results. These results may span over several pages, and hence, a well designed pagination bar becomes essential for easy navigation. This blog deals with how we created the pagination bar in Susper. This is how the pagination bar in Susper looks:

There are a maximum of 10 pages displayed at any point of time.
At times you may have lesser results too:

where you can either directly click on a page or use the Previous and Next buttons for navigation. As you move along the pages, this is how it looks:

We will now see how we go about creating this bar.
The html source code( with a line by line explanation of the code):

<div class=“pagination-bar”>
<div class=“pagination-property” *ngIf=“noOfPages>1”>
<nav arialabel=“Page navigation” *ngIf=“(items$ | async)?.length!=0”>
  • Previous button is used to decrease the current page number, clicking on the first S in ‘Susper’ also accomplishes this task. Notice that this button is to be displayed only if you are not already on the first page of Susper.
<li class=“page-item” *ngFor=“let num of getNumber(maxPage)”><span class=“page-link” *ngIf=“presentPage>=4 && presentPage-3+num<=noOfPages” [class.active_page]=”getStyle(presentPage-3+num)”
(click)=”getPresentPage(presentPage-3+num)” href=“#”>

[class.active_page]=”getStyle(presentPage-3+num)” class=“page-text”>U

<span class=“page-link” *ngIf=“presentPage<4 && num<=noOfPages” [class.active_page]=”num+1 == presentPage (click)=”getPresentPage(num+1)”

[class.active_page]=”num+1 == presentPage class=“page-text”>U</span>


  • The above lines specify that we want to update our pagination bar only if the user has navigated more than the first three pages  
  • class.active_page gives correct css for the active page and getStyle() tells whether that particular page is active or not  
  • getPresentPage() uses the current page number to calculate which results to display  

<li class=“page-item”><span class=“page-link” (click)=”incPresentPage()”>

class=“page-text next”>SPER

<li class=“page-item2” *ngIf=“!getStyle(maxPage)”><span class=“spl” (click)=”incPresentPage()”>



  • This part is used to increment the present page, and show the next/SPER message. Notice that it should be displayed only if you are not already on the last page

The attached typescript functions:

incPresentPage() {
this.presentPage = Math.min(this.noOfPages, this.presentPage + 1);
}decPresentPage() {
this.presentPage = Math.max(1, this.presentPage 1);
  • incPresentPage() increments the present page, if possible(that is you have not reached your maximum pages already).
  • decPresentPage() decrements the present page, if possible(that is you have not reached page 1 already).

getStyle(page) {
return ((this.presentPage) === page);
  • getStyle() returns true if passed page is the present page, useful to apply different css classes to the active page

getPresentPage(N) {
this.presentPage = N;
let urldata = Object.assign({}, this.searchdata);
urldata.start = (this.presentPage 1) * urldata.rows; queryactions.QueryServerAction(urldata));}
  • getPresentPage () is used to change the page, and navigate to the page, with the correct rows of data

And you are done! You now have a working pagination bar to plugin at the bottom of your search results!

You can check out this elaborate tutorial on implementing Pagination bars from w3 schools :

Making the footer-navigation bar stick to the bottom in Susper

In Susper, we have a navigation bar as a footer, as shown:

Previously this footer-navbar would appear immediately after the content, even if it was in the middle of the page. This is how the footer would appear:Since this could be a very common problem on a lot of websites, this blog deals with a simple hack for it.  

  1. Design your footer navbar as you please. You need not use any predefined bootstrap classes. You also need not specify any parameters regarding the position of the navbar (relative, absolute etc.).
  2. Enclose the rest of the data on your webpage in a div tag, do not forget to mention a class name or id name for the tag.  
  3. Now comes the simplest trick: Set a minimum height for your div! It is advisable to use vh (viewport-height) as your unit of measurement since it is easy to estimate how much of the viewport needs to be covered by your width.

This is how it is used in Susper:

Remember that each vh corresponds to one-hundredth of the viewport total height. So 100 vh here will mean a minimum height of the full viewport.

You can check the Susper repository for the source code or go through this link for alternate ways to create a sticky footer at the bottom.

Deploying Angular 2 application using GitHub Pages

In recent months I have started working with Angular 2 technology as my project is based on this tech stack. Angular 2 is one of the famous frameworks of JavaScript. The project name is ‘Susper’ which is currently being in development stages under FOSSASIA. In FOSSASIA, to be a good developer everyone follows good practices. One of the good practice is providing a live preview of the fix done in a pull request related to a particular issue. It was not simple to deploy test pages as it looks on GitHub pages. I read a lot of StackOverflow answers and surfed google a lot to find a solution. Then I came to the solution, which I’ll be sharing with you in this blog.

I’m assuming your Angular 2 app must be using webpack services and the latest version of Angular has been installed. Firstly, be sure Angular CLI must be updated. If not, then update the Angular CLI to a new version. You must update both the global package and local package of your project.

Global package:

npm uninstall g @angular/cli
npm cache clean
npm install g @angular/cli@latest

NOTE – Make sure to install local packages, you must be inside the project folder.

To make deployments easier, follow these steps after updating global and local packages –

Install angular-cli-ghpages :

npm i g angularclighpages

This command is similar to the old github pages:deploy command of @angular/cli and this script works great with Travis CI.
After installing you should see the changes in the package.json as well:

“devDependencies”: {
    “angular-cli-ghpages”: “^0.5.0”

After updating the global and local package you will notice a new folder named ‘node_modules’ has been created. Now the magic part comes to play here!

Add deploy script:

In package.json file add the following deploy script –

“scripts”: {
    “deploy”: “ng build –prod –aot –base-href=/project_repo_name/ && cp ./dist/index.html ./dist/404.html && ./node_modules/.bin/angular-cli-ghpages –no-silent”

We have setup the required dependencies to deploy test page. Now, here it comes to generate a live preview:

Steps :

git checkout working_branch
ng build
npm run deploy

We have successfully deployed the repository to GitHub pages. To refer live preview go here –

How did it work out?

Well, this is the easiest way to deploy any angular 2 apps on GitHub pages. The only disadvantage of deploying to GitHub pages is that we have to always perform a manual build before providing a live preview whenever some changes have been done in that particular branch.