Category Archives: CS-343

Understanding Angular with Tetris

For this week’s post I read through Michael Karén’s article, “Game Development: Tetris in Angular.” As the name suggests, this article demonstrates how to make a Tetris game in Angular. This is a great example project that shows many of Angular’s functionalities without being too complex. It covers topics introduced in CS 343: components and templates, and other topics like styles and event listeners. The author’s project code can be viewed on GitHub for further examination.

The project contains three components (with @Component
decorator): app, board, and piece. The app component is the main component that
uses the board component as a template. The board component handles the board
UI and injects the game logic from GameService. And lastly, the piece component
handles the UI and properties of the Tetris pieces.

Templates are used in two ways in Karén’s game. The app-root
which uses another component as its template by using the custom tag
<game-board></game-board>. The game-board uses a URL as a template,
which is defined in the board component’s HTML file. This HTML file defines how
both game-board and, by extension, app-root are rendered on the page.

The injectable class (with @Injectable decorator)
game.service contains much of the game logic. As an injectable, game.service’s
methods are accessible to board.component when game.service is injected in
board.component, located at the example code’s line 72 with “constructor(private
service: GameService) {}.” This is useful as it is cleaner to separate the responsibility
of the game logic and the UI logic from each other.

The styles are defined in a Cascading Style Sheet or CSS file.
The CSS file is used to define how some of the HTML elements are designed. CSS makes
HTML design simpler with its more intuitive interface.

I learned a new decorator from this article, @HostListener.
This decorator can be used to define the program’s response to user
interaction. In this article’s project uses @HostListener to define how the game
board responds to the specified keystrokes.

The JSON methods stringify and parse were also new to me. JSON.stringify will convert an object into a string. JSON.parse on the other hand, converts a string into a JSON object.

Reading through this article and examining the project’s
code has helped my understanding of Angular and HTML tremendously. I recommend Michael
Karén’s article, “Game Development: Tetris in Angular,” to those who are
looking for a fun example of an Angular program.  Being able to see all the parts of the
program and how they work together has made Angular more accessible for me and
has provided an excellent resource for possible projects in the future.

Article referenced:

From the blog CS@Worcester – D’s Comp Sci Blog by dlivengood and used with permission of the author. All other rights reserved by the author.

Angular Components

This past week, I began to work with REST API frontend code
using the Angular framework in CS-343. The introductory class activity taught
the basics about setting up and working with an Angular project as well as some
useful properties of Angular (such as *ngIf) that I definitely see myself using
in the future. However, the activity did not go into much detail about how to
create and manipulate Angular components to create more interesting UIs. While
researching Angular on my own, I came across a blog post from Angular
University titled “Angular Components – The Fundamentals.”

The blog can be found here:

As someone who has enjoyed creating UIs in Java using Swing
components, this blog immediately caught my attention. I expected it to help me
create UIs for server-based applications that would be more interesting than
the basic layout I worked with in class. However, while this blog did not go
into too much detail on the creation of UIs, it has certainly helped me to
better understand the fundamental properties of Angular components. The information
I learned from this blog will undoubtedly be useful as I begin to work more
in-depth with Angular components in my final project for CS-343. I decided to
share this blog because I think that others who are new to Angular will also find
it to be a useful introduction to Angular components.

The blog starts by providing a basic introduction to Angular components, as well as browser components in general, using short example code. It then discusses in detail the two main aspects of an angular component, properties and events, and explains when to use them and when to avoid using them. I think the blog did a great job explaining properties and events in simple terms and clearly stating when not to use them. I especially liked how the blog links properties and events to input and output, respectively. This association helped me understand when to make use of properties and events in Angular projects, since I already have experience working with input and output of components in Java. I also think the example code in this blog is simple enough that it can easily be referenced while working on other projects. I certainly see myself referring back to these examples as I start working with Angular components on my own to help myself understand the correct syntax for implementing properties and events. Finally, this blog has demonstrated to me how to create familiar components, such as a scrollable list, and it has taught me how to change aspects of components, such as their color. The information in this blog has helped me understand the fundamentals of Angular components and how to work with them in applications. I will certainly be referring back to this post as I begin to work on my final project this week, as it is a great resource to help new Angular developers to understand Angular components.

From the blog CS@Worcester – Computer Science with Kyle Q by kylequad and used with permission of the author. All other rights reserved by the author.

FPL&S 1: Getting to Know Angular

For my final project in my software construction and architecture class, I will be writing a 5-post series for Final Project Learning and Status (FPL&S). This project will be using Angular, Typescript, and Node Package Manager (npm). I am not familiar with these tools, but I have learned my lesson before that one should fully understand the technologies they’re using before they start a project. I have spent about 10 hours this week tinkering with Angular, reading blogs, watching tutorials, and of course referencing Angular documentation, with the goal of understanding the architecture as a whole.

My first question: why did I have to download Node.js? The answer boils down to requiring npm, which is packaged with Node.js. Npm allows users to share packages, and Angular requires quite a few packages to run. Npm takes care of this. Of course, it also installed Angular itself.

I was also confused about which files were doing what in a pre-configured project, but after playing with the code and making modifications, this started becoming second-nature, so I won’t go into detail on that. However, learning the concepts behind each file was much more important.

Traversy Media released an Angular Crash Course video which I found to be quite comprehensive and helpful in understanding the framework as a whole. Many of these concepts were learned in practice, but it is nice to be explicitly told some things to remove doubt. The video described how UI “Components” are used and built. Particularly useful were the descriptions of using a constructor to import services that will be used, and that selector was defining the tag to be used in HTML.

Modules, called NgModules, are another important concept, central to Angular. In a single-page web app you might only have a single NgModule, but in larger systems they help improve the modularity of an application, just as modules in Java or other languages. A single NgModule, however, can have many Components. Components can also be reused and nested, but should be considered a view, the goal of which is to create a user experience.

My final project will tie in with my independent study Android app next semester. My first idea was to implement audio recording that will also be necessary for my mobile app, but this turned into a much bigger challenge than expected. Due to the nature of my mobile app, I feel it will be better to start with a web front-end that can pull from data already stored in a cloud database, in order to display metrics, charts and a summary of results. Learning about Angular Observables will likely help to perform asynchronous uploading.

I’ve learned much more than what I’ve written up here, but this blog post addresses what I feel was most relevant to my project and learning Angular. Since this blog is documenting learning experiences, I welcome comments, corrections, and suggestions if anyone thinks it will help.

From the blog CS@Worcester – Inquiries and Queries by ausausdauer and used with permission of the author. All other rights reserved by the author.

A Different Type of Angles

I decided to learn more about angular since it peaked my interest in class and in general. in my search for more information on Angular, I found “Introduction to AngularJS” by GeeksForGeeks. This post explains the strengths and important things to know about Angular and some of the key features of Angular. some key points from the post are that its easy to use and requires little understanding of different coding languages like HTML, JavaScript, and CSS. Angular saves time as well and avoids unnecessary code. Angular is a powerful framework that allows the developer more control over their applications and web resources. Angular is also unit test ready which helps the developer even more in there processes of creating applications and resources. Angular has Data Binding which means that the developer does not need to continuously update the HTML file or create a special code to bind the data. This keeps data consistent and updated with the most recent version of an application or resource that the developer provides.
Angular seems to make web development easier than ever and gives people the templates and tools needed to create powerful and intuitive applications to suit their own needs. From my short experience with angular, i felt confident and powerful while using the framework and wasted less time than expected had i tried to create a web application without it. I felt in control and could see the real time changes that were occurring in my local website due to the changes I was making. Angular has been for sometime one of the three major frameworks for web developers and the other two are React and Vue. I’m unsure about the other too languages are better or worse or have advantages over Angular, but at this point in time Angular seems like a strong and good choice for my future with any type of web development. the one thing that i think makes angular so appealing to me and others is that the data is bonded and you don’t need to constantly change things to reflect one change in a web application or resource. This framework is something i could see myself using in the future or something like it for web development because it simplifies a larger more difficult job and allows people with enough information to traverse its power and harness that power to create powerful applications. I can’t wait to learn even more about Angular and how to use it effectively.
link to article referenced:

From the blog CS@Worcester – Tyler Quist’s CS Blog by Tyler Quist and used with permission of the author. All other rights reserved by the author.

The Single Responsibility Principle

Several weeks ago, we briefly discussed the SOLID design
principles in CS-343. This discussion was supposed to lead into a homework
assignment where we would research a couple of principles, but since this never
happened I decided to research a SOLID principle for a blog post instead. In
this post, I will be focusing on the Single Responsibility Principle, or SRP
(the ‘S’ in SOLID). This principle declares that a class should have only one
reason to change, or in other words, a single responsibility. It sounds like a
simple concept, but actually implementing it can be challenging. My research
into the SRP helped me come across a blog post by Patrick Smacchia titled “SOLID
Design: The Single Responsibility Principle (SRP),” which defines guidelines
that may help make the principle easier to follow.

The blog can be found here:

In the blog, Smacchia explains that the SRP is not as simple
to follow as it sounds, because different programmers may define a responsibility
or a reason to change in different ways. For this reason, he approaches
the principle based on its fundamental purpose of determining which logic
should be in which class. From this approach, he explains several aspects of
the SRP using example code, and he provides a set of concrete guidelines that
can help enforce the principle. I chose to share this post because Smacchia’s
approach to explaining the SRP has helped me understand it better by getting me
to think about it from a more fundamental perspective. I also think his
guidelines would be useful to any programmers, myself included, who intend on
following this principle in their projects.

I certainly intend on referring back to the guidelines
included in this blog to ensure that my future projects follow the SRP. Although
there are a couple I don’t fully understand, such as the one on POCO classes, I
think the others will greatly help me adhere to the SRP. His suggestion to keep
logic related to different functions separated into different classes makes
sense thanks to his Employee example, which I will refer back to when deciding
which functions should be separated into different classes. I found Smaccia’s
discussion on cohesion especially interesting because it exposed me to the Lack
of Cohesion Of Methods metric, or LCOM, which is used to actually quantify how
cohesive a class is. It surprised me that a more complex class can have a lower
LCOM score than a simpler one, and that a class’ simplicity does not represent
its adherence to the SRP. I will definitely refer back to this blog to help me
ensure that my own classes keep a low LCOM score even as they grown more
complex as a way to follow the SRP. I have certainly had issues with classes
getting too large and doing too many things in the past, and I think learning
more about the SRP from this blog will help me avoid this problem in the future.

From the blog CS@Worcester – Computer Science with Kyle Q by kylequad and used with permission of the author. All other rights reserved by the author.

Apps Made Easy With Angular

If you have ever been around anything web-based, there is a
good chance you have heard or come across angular. Angular for those unfamiliar
is a framework that allows for a wide range of possibilities. Angular all stems
from 4 main parts: components, dependency injection, property bindings and
typescript. Components are what Angular is entirely composed of. Most things
created in Angular are components or collection of components. While there are still
a few other concepts to angular, components are the most prominent. Components
are usually comprised of HTML, CSS and JS but with angular, these are all
combined into an easy to manipulate sense to allow for customization of the
components. The next part of angular is the dependency injection which helps
largely with dependency management. Dependencies are all in a collection together
and when new components are created, the dependency for that object is
automatically created and put into the collection alongside the other dependencies.
This allows for the user to easily streamline dependency management as angular
is able to “automatically” create and track dependencies. The next main aspect
of angular is the property bindings. What this means is that the data that the
app contains is separate from the what is being presented. This allows for the
user to make changes to this data and automatically have it update and be
displayed on the presentation side. This allows for the user to seamlessly update
anything needed in real time. The last part of angular is the support and use
of typescript. Javascript, for the ones unaware, is a subset of typescript.
Typescript allows for a very straight forward approach to writing javascript.
The user is able to write the code needed in typescript and it will be automatically
generated into javascript to be used by the app.

The main benefit of angular is allowing for users to easily
be able to build large scale apps with everything being self-contained in the program.
A lot of the complicated processes that went along with developing apps are now
very easy to be implemented with Angular. People that are not skilled in javascript
generally have a much easier time adapting typescript due to the fact that the syntax
is not all too different from java. Most skilled programmers are able to pickup
and implement typescript rather quickly. This allows for almost anyone to be
able to create and build large scale apps without having to personally be
responsible for many of the complications that would prevent people from trying.

If you want to learn more, this website has a great overview
of Angular:

From the blog CS@Worcester – Journey Through Technology by krothermich and used with permission of the author. All other rights reserved by the author.

Javascript vs. Typescript

As someone fairly new to coding, learning new languages is both fun and painful. When I heard we were going to be doing some web development, I figured Javascript would be involved, and I had a brief moment of panic. I am a frequenter of subreddits like /r/programmerhumor, or other humor-based tech blogs, and there is a lot of dogpiling on Javascript as a language. It gets a lot of flak for being very weakly typed, and for its default behaviors utilizing this weak typing leading to a lot of wacky and confusing results for people who aren’t deeply familiar with the language. A quick example:

When I discovered we would be using Typescript (And what Typescript was), it was a bit of a relief. The way that the language looks just feels more comfortable to me, especially as someone who has mostly been learning Java. I have been trying to expand my horizons as of late, and wanted to look into people that may feel the opposite. Maybe the verbosity and strictness of a strongly-typed object oriented language is bad if you know what you’re doing, and I found a very interesting blog expressing just that.

In the blog post “Shit Javascript Coders Say” by Dave Sag found here:,
he utilizes a very pointed and crass writing style to express his distaste for OOP and strong-typed languages in general compared to Javascript. He also does not like Typescript. One reason I find this funny is because in this Software Architecture class I am writing this blog for, there is a big focus on creating interfaces, organizing classes, and figuring out the best ways to group and create objects. These are all things, according to Dave Sag, that are not needed in Javascript, and that Typescript “encourages the use of these practices as a weak, wobbly crutch” (paraphrasing).

I found this juxtaposition very amusing, and would be very interested in going down the rabbit hole more and finding out about best pure Javascript practices, or if Mr. Sag’s views are commonly held in some communities (I found plenty of blog posts praising Typescript, for what it’s worth).

In my brief time with Typescript so far, I have found it a bit verbose and clunky (though I am certainly a neophyte coder). Hopefully as I continue to learn, these distinctions become more clear and I can post an updated perspective.

From the blog CS@Worcester – Alan Birdgulch&#039;s Blog by cjsteinbrecher and used with permission of the author. All other rights reserved by the author.

Getting Angular

The topic for my post this week is Angular. CS 343, Software construction, design, and architecture, introduced REST API frontend last week. I did not have a good grasp of what Angular is, so I read the article “Angular Tutorial: Getting Started With Angular 4”, by Shubham Sinha. The article breaks down Angular into easy to understand parts which are then explained thoroughly.

The article begins with describing the general history of
Angular and why it was designed. Originally AngularJS, Angular was designed for
the use in designing SPAs (Single-Page Application). SPAs are useful as they do
not require an entire page to be refreshed. Instead SPAs only refresh necessary
components. This allows for SPAs to act similarly to desktop applications.

The article then begins its tutorial, though I would describe
it as an overview of the details of Angular projects. The author goes into the
different parts of Angular and describing them each in detail.

  • Modules:                           
    Chunks of code with a specific task, such as classes.
  • Components:                   
    Code that use API to control sections of the screen. Contains instructions for
    client-side GUI.
  • Templates:                        
    HTML tags that describe how to render components.
  • Metadata:                          
    The code that informs Angular on how to process a class.
  • Data
    The connection used to tie parts of a template to parts of a component. An easy
    connection for data state and data events.
  • Directives:                         
    Logic code for manipulating data: adding, removing, changing.
  • Services:                             
    A wide category for encompassing anything an application my need.
  • Dependency

    Allows Angular to create new instances of a class with all its dependencies
    that can be “injected” into another class.

From what I understand, the page code will be divided into
modules. The page view will be divided into components that use templates and
metadata to determine how to display the component. Directives are logic code
that manipulate data. Data binding allows for easy access to a data’s state and
events. Dependency injection inserts an instantiation of a class with all its
dependencies. Finally, services are simply anything an application may need:
value, function, feature.

I found that after reading this article I have a better
understanding of Angular. Angular can be used for client-side rendering of
data. By separating the page into several different components, Angular can create
SPAs that are dynamic and responsive. This article is informative and accessible,
I highly recommend this article to anybody who is getting acquainted to

Referenced Article:

From the blog CS@Worcester – D’s Comp Sci Blog by dlivengood and used with permission of the author. All other rights reserved by the author.

SOLID Principles

This will be two parts post, I will talk about the SOLID principles and try to cover all of them from the way I understand SOLID,

First SOLID was introduced by Robert C. Martin (Uncle Bob), in his 2000 paper Design Principles and Design Patterns. Uncle Bob also well known for his book Clean Code, I studied this book in my CS-338 class, it was great book in changing the way of coding. and how to writ a clean code.

Going back to SOLID. SOLID is a shortening for 5 important design principles Object Oriented Programming

S — Single responsibility principle

O — Open/closed principle

L — Liskov substitution principle

I — Interface segregation principle

D – Dependency inversion principle

I will talk about the first tow principles in this post.

Single responsibility principle

It means that every class and module should be responsible
or have responsibility of a single part of the software functionality. It is
like do one thing and do it well. Uncle Bob defines a responsibility as a ‘reason
to change’ which means that the class or the module don’t need more than one reason
to be change.

For example lets look to this code:

This code violates the SOLID first principle, the method CreateBlog() has to do many responsibilities, create a Blog, and log an error in the DB and also log an error in the file. which is absolutely the opposite of the Single responsibility principle

class Author
void CreateBlog(Database db, string publishtText)
catch (Exception ex)
db.LogError(“There is an Error: “, ex.ToString());
File.CheckAllText(“There is a Local Errorn in.txt”, ex.ToString());

Lets try to fix the problem in the code above.

class Blog
private ErrorLogger errorLogger = new ErrorLogger();

void CreateBlog(Database db, string publishtText)
catch (Exception ex)

class ErrorLogger
void log(string error)
db.LogError(“There is an Error: “, error);
File.CheckAllText(“\There is a Local Errorn in.txt”, error);

We created two classes each one of them will handles one responsibility,
and that will no longer violate the single responsibility principle.

Open/closed principle

It means that the software entities (classes, modules, functions, ….) has to be closed for modification however has to be open for extensions.

We know from the Object-Oriented Programming or OOP, the polymorphism , and I posted a blog explaining about polymorphism. In another word we need to create inheritance or implementing an interfaces in the code to make sure it is compliant with the open/closed principle

lets look to this code and see whether it is applying the Open/closed principle

class Blog
void CreateBlog(Database db, string publishtText)
if (publishtText.StartsWith(“!”))

What we want in this code is to do a exact one thing which is the every time a published Text start with the character ‘!’, the code is violates the open/closed principle. If in the future we needed wanted to include mentions all the published text starting with ‘#’, then modifying the class with an another ‘else if’ is a must added to the method().

Lets try to fix the problem in the code above.

class Blog
void CreateBlog(Database db, string publishtText)

class TagText : Text
override void CreateBlog(Database db, string publishtText)

It is much easier to create extended behavior to the Blog object by using inheritance and overriding the CreateBlog() method.

That is all I have for this week, and next week I will continue on the SOLID principles and talk about the other three principles .

From the blog CS@Worcester – Shams&#039;s Bits and Bytes by Shsms Al Farees and used with permission of the author. All other rights reserved by the author.

Understanding Typescript

Let’s start by discussing javascript a bit. Javascript is currently a must know programming language in the computer science world. It is widely used for web development on both front-end and back-end development. Javascript can also be found in many other fields of development including mobile apps, desktop apps, and game development. 

Javascript language is quite user friendly and can even be considered easy to learn but it doesn’t come without its concerns of course. The same code you’ve written may work differently when used in different browsers such as Google Chrome versus explorer, or safari, for example. Javascript is also very stripped down so it can be easy to create errors by mistake especially for beginners. An example of this is that Javascript is dynamically typed. Programs don’t know the types of variables until they are assigned at runtime and then they must do an awful lot of referencing to figure out the type depending on the size of the program. Since types are not required there are no compiling errors or messages to tell you what you are doing wrong. It leaves a hard traced error if or not careful when working with your code. 

Now moving on to Typescript!

Typescript is a superset of Javascript which means it contains all the same functionality of Javascript as well as added features. Typescript compiles to plain Javascript so any code you write in Javascript will run just fine in Typescript, as long as you have written it correctly of course. The big additions of Typescript are type annotations, interfaces, and classes. 

As opposed to Javascript, which is dynamically typed, Typescript uses static typing. Static typing means that things like variable types can be checked at compile time since variable annotations are available. The code will still run if you have an error but you will receive a message warning you about the specific error that was detected. Also depending on your IDE it may offer the function of displaying errors to the user while they are typing. If you want to take advantage of this functionality then you can check out the Visual Studio Code IDE, which contains that function.

I chose to blog about this subject because I am a newcomer to this language and material. I figured if I did some research on my own and actually typed out the words then it would all become more clear to me what the relationship of Typescript was to Javascript and what they are used for in the real world. I feel now that I have this general overview and understanding of the language and its use that I can now conceptualize my own uses for it. I’m looking forward to implementing what I have learned about Typescript into my own projects.

Lease, Diana. “TypeScript: What Is It & When Is It Useful?” Medium, Frontend Weekly, 31 Jan. 2018,

From the blog cs@worcester – Zac&#039;s Blog by zloureiro and used with permission of the author. All other rights reserved by the author.