Fixing Infinite Scroll Feature for Susper using Angular

In Susper, we faced a unique problem. Every time the image tab was opened, and the user scrolled through the images, all the other tabs in the search engine, such as All, Videos etc, would stop working. They would continue to display image results as shown:

Since this problem occurred only when the infinite scroll action was called in the image tab, I diagnosed that the problem probably was in the url parameters being set.

The url parameters were set in the onScroll() function as shown:

onScroll () {
let urldata = Object.assign({}, this.searchdata);
this.resultDisplay = ‘images’;
urldata.start = (this.startindex) + urldata.rows;
urldata.fq = ‘url_file_ext_s:(png+OR+jpeg+OR+jpg+OR+gif)’;
urldata.resultDisplay = this.resultDisplay;
urldata.append = true;
urldata.nopagechange = true; queryactions.QueryServerAction(urldata));

The parameters append and nopagechange were to ensure that the images are displayed in the same page, one after the other.
To solve this bug I first displayed the query call each time a tab is clicked on the web console.
Here I noticed that for the tab videos, nopagechange and append attributes still persisted, and had not been reset. The start offset had not been set to 0 either.
So adding these few lines before making a query call from any tab, would solve the problem.

urldata.start = 0;
urldata.nopagechange = false;
urldata.append = false;

Now the object is displayed as follows:

Now videos are displayed in the videos tab, text in the text tab and so on.
Please refer to results.component.ts for the entire code.


  1. On how to dispatch queries to the store:
  2. Tutorial on the ngrx suite:

Creating an Infobox for Mobile View Using Angular in Susper

In Susper, the Information and Analytics boxes disappeared for widths smaller than 1100px, since they were too big to fit in the existing page layout.
In Laptop view:

In Mobile view:

Hence we decided to design a new Info-cum-Analytics box for mobile devices, where the Analytics are displayed only if the ‘Show Analytics’ button is clicked and they are hidden on clicking the ‘Hide Analytics’ button.

The following is the html code for the Infobox:

<div class=“combo-box”>
<button class=“btn” id=“toggle-button” (click)=“BoxToggle()” type=“button” datatoggle=“collapse” datatarget=“#statbox” ariaexpanded=“false” ariacontrols=“collapseExample”>
{{boxMessage}} Analytics
<appstatsbox class=“collapse” id=“statbox”></app-statsbox>

We can make the following observations:

  • The combo box has both the Info and the Stats box, in addition to a button, which toggles the display status of the Analytics box.
  • To display the appropriate message on the button, we have a special function called BoxToggle() which sets the value of boxMessage()
  • The data-toggle attribute of the button has been set to collapse and the data-target is statbox
  • The statsbox has the class collapse, so that it collapses on clicking on the Toggle button.

The typescript code is as follows:

BoxToggle() {
if (this.boxMessage === ‘Show’) {
this.boxMessage = ‘Hide’;
} else {
this.boxMessage = ‘Show’;

This code thus effectively toggles between the messages Show and Hide, if the button is clicked when the message says Show, it changes to Hide and vice-versa

The CSS code:

@media screen and (min-width:768px) {
div.combo-box {
display: none;

The css code ensures that this combo-box is displayed only for widths less than 768px (only mobile and tablet screens).

To view the entire code you can check results.component.html and results.component.css in the Susper repository.


  1. W3 Schools for Collapsible buttons and their implementation:
  2. Official Bootstrap documentation for collapsible buttons:

Writing Browser Specific CSS for Susper in Angular

In Susper, we were facing a unique problem for Information box and Analytics box alignment.
At a width of around 1290 px, the boxes fit perfectly in Firefox as shown:

However, they were slipping to the next line in Google Chrome browsers for the same dimension(1290 px)

The solution to this issue was to write browser-specific CSS.
The two most commonly used browser specific tags are

  1. @-moz-document url-prefix() { }: This tag is used to target the Mozilla Firefox browser in particular. Anything written within the curly braces will not apply to any other browser.
  2. @media screen and (-webkit-min-device-pixel-ratio:0) { }: This tag is used to target all browsers that support webkit such as Chrome, Safari etc.

For our problem, we need to use @media screen and (-webkit-min-device-pixel-ratio:0) { }
This was how the code was written for both the components (Information box and Analytics box). Please refer to infobox.component.css and statsbox.component.css for the entire code.

@media screen and (-webkit-min-device-pixel-ratio:0) {
@media screen and (max-width: 1300px) {
.card {
width: 366px;
@media screen and (max-width: 1280px) {
.card {
width: 366px;

As a result of this snippet of code, we see the following effects:

  • In Chrome, the boxes change to a smaller width at 1300px itself, thus preventing it from slipping to the next line
  • In Firefox, the boxes change to a smaller width only at 1280px, and not at 1300px, thus achieving the exact design we envisioned.

This is how the display finally looks in Chrome:


  1. Stack overflow on specific CSS tags for Chrome:
  2. Stack overflow on specific CSS tags for Firefox:

Making a Sticky Top Navigation bar for Susper using Angular

A lot of websites, require a top navigation bar that sticks to the top, irrespective of the screen dimension size. This blog deals with how the top navigation bar was made sticky in Susper.

  1. Using the correct Bootstrap classes. Notice the code enveloping the navigation bar.

<nav class=“top-nav navbar navbar-static-top navbar-default”>


class=“navbar-header” id=“navcontainer”>


Points to note:

  • Using navbar and navbar-default creates a standard gray navigation bar.
  • Using navbar-static-top makes the navbar stick only to the top of the page and disappear on scrolling down.
  • Using container-fluid creates a container for the contents of the navbar with wide margins
  1.  Now we also need to write some personalized CSS code. Notice the classes navcontainer and  top-nav. This is the CSS code for these classes:

margin-bottom: 0;
#navcontainer {
height: 65px;
width: 100vw;
}#navcontainer ul {
margin: 0;
padding: 0;
list-style-type: none;

Points to note:

  • Margin and padding can be set according to how the navbar should look. Click here to know the difference between margins and padding.
  • The height has been customized to 65px in Susper, with a width of 100vw(entire viewpost width).
  1. Lastly, if your navigation bar is inside the body tag, remember that by default, body has a top margin of 57 px. As a result you may see an extra white space on top of your navigation bar. To remove this:
  • Move the navigation bar code out of the body tag. If you can’t then,
  • Place your navigation bar in a container ( resultContainer on the Susper result page) and write this in your CSS file.

margin-top: -57px;


Making Customized and Mobile Responsive Drop-down Menus in Susper using Angular

In  Susper, the drop-down menu is customized with colorful search icons and we wanted to maintain the same menu for mobile screens too, however the drop-down menu disappeared for all screens with width less than 767px. This blog can be used to learn how to create css classes for such drop-down menus without using any bootstrap.
This is how the issue was solved.

  1. Replacing standard bootstrap classes : The drop-down menu blocks had a source code as follows:






Using col-sm-4 will do the following

  • For widths greater than 767px: Divide each row into four equally sized columns.
  • For widths smaller than 767px: Stack all the columns on top of each other.

Since the drop-down menu’s design was to remain intact, I made the following changes:

  • Replace row with menu-row
  • Replace col-sm-4 with menu-item

Now I wrote personalized css for these classes.

width: 267px;
gridtemplatecolumns: 1fr 1fr 1fr;
background-color: white;
display: inlineblock;
width: 86px;
  • Width: It is used to set the width of the div class, each row now has a width of 267px, with each column in it having a width of 86px.
  • Grid-template-columns: It is used to layout the structure of the template, here 1fr 1fr 1fr represents that there will be three columns in a row.
  • Display: The display is set to inline block to overwrite the default property of the div element to start in a new line.
  1. Custom css for small screens : In standard bootstrap, for screen sizes less than 767px, dropdown class has properties like transparent background, no border etc. that need to be over written. So we add a new id for the div tag as shown:

<div id=“small-drop” class=“dropdown-menu”>

/** Now we add css for it, as shown: **/
@media screen and (max-width: 767px) {
position: absolute;
background-color: white;
border: 1px solid #cccccc;
right: -38px;
left: auto;

  • Position : absolute is used to make sure all our values are absolute and not relative to the higher div hierarchically
  • Border: The values for the border represent the following respectively: Thickness, Style and Color.
  • Auto: Here the value auto for left signifies that there is no fixed value for the left margin, it can take the default value


  1. For working of grids in Bootstrap:
  2. A useful article for difference between id and class:


Making Autocomplete Box Compatible with the Search Bar using Angular in Susper

A major problem in Susper was that we were using the same components on different pages, with different styling properties. A major issue was that the Autocomplete box was not properly aligned in the index page and looked like this:

This was happening because the autocomplete box width was set for 634 px, a width perfect for the search bar in the results page. The index page had a search bar of width 534 px, and the autocomplete box was too large for that.
Here is how the issue was solved:

  1. Changing the suggestion box html code:

id=“sug-box” class=“suggestion-box” *ngIf=”results.length0”>


The code uses *ngIf which is why setting the autocomplete box width using the typescript files becomes impossible. *ngIf does not load the component into the DOM until there are results, hence we didnot have the autocomplete box in the DOM until after the query was typed in the search bar. That was why we could not set its width, hence it was decided to remove this attribute. Using the ‘hidecomponent emitter’ is a better option here (used in the typescript file).

@Output() hidecomponent: EventEmitter<any> = new EventEmitter<any>();
if (this.results.length === 0) {
} else {

See autocomplete.component.ts for the complete code.

  1. It is now required to dynamically change the id of the suggestion-box depending on the page it is on, and apply the correct CSS.

Here is the html code:

<div [id]=”getID()” class=“suggestion-box” *ngIf=“results”>

The id of the suggestion box will now depend on the value returned from the function getID(), defined as follows:

getID() {
if ( this.route.url.toString() === ‘/’) {
  return ‘index-sug-box’;
} else {
  return ‘sug-box’
  • We first check if the route url is simply ‘/’ (which implies it is in the index page).
  • If yes the id is set to index-sug-box otherwise to sug-box.

Now we can write extra CSS properties for the index-sug-box id as follows:

width: 586px;


  1. For basic javascript functions:
  2. To understand components in Angular:


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.