Monday vhandit #1

This is the first post in a series of articles called "Monday vhandit". You can go to the original post by clicking on each head title.

Character encodings: essential concepts

This article points out why Unicode matters and differentiates among concepts: character sets, coded character set (unit is code points), and character encoding.

Explained from First Principles: the Internet

The very structural and well-explained article contains almost concepts of the Internet. I really appreciated the author's effort put on that post.

Dev Community - DevDojo

I just joined this community. DevDojo is really a developer-oriented platform. It is very nice, easy, fast, and sufficient to write (Markdown supported) and search for a post. The best of it, you also have a personal blog for your posts at "<your_username>.devdojo.com". My username is vnnvanhuong

Everything you need to know about HTTP security headers

A good collection of HTTP security-related headers. Moreover, its content is structured in a timeline manner when a header is introduced to solve a specific problem.

A history of elliptic curves in tweets

A very fun and creative post for knowing more about the history of elliptic curves. It is fun for me because I am reading "Random Curves: Journeys of a Mathematician" by Neal Koblitz.

Comments

Make simple music program with beep(freq, duration) with Pascal

Pascal is my first programing language when I have studied in high school. It was really exciting for me. :) The Pascal programming language was created by Niklaus Wirth in 1970. It was named after Blaise Pascal, a famous French Mathematician. It was made as a language to teach programming and to be reliable and efficient. Pascal has since become more than just an academic language and is now used commercially . I tried to make a simple music program by using Lazarus IDE on MS Window 7, 64-bit. It frustrated me a few times how difficulty to use Sound command to make a sound. Sound did not work on my compiler and my platform anymore. So far, I just could use beep(freq, duration) from window unit to implement my work. Here is my code. ;) program mysong; uses Windows, crt; const C: Integer = 512; { x = A * EXP(LN(2)/12)} C_: Integer = 542; D: Integer = 574; D_: Integer = 608; E: Integer = 644; F: Integer = 682; F_: Integer = 723; G: Integer = ...

Styling Sort Icons Using Font Awesome for Primefaces' Data Table

So far, Primefaces has used image sprites for displaying the sort icons. This leads to a problem if we want to make a different style for these icons; for example, I would make the icon "arrow up" more blurry at the first time the table loading because I want to highlight the icon "arrow down". I found a way that I can replace these icons with Font Awesome icons. We will use "CSS Pseudo-classes" to achieve it. The hardest thing here is that we should handle displaying icons in different cases. There is a case both "arrow up" and "arrow down" showing and other case is only one of these icons is shown. .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s { background-image: none; margin-left: 5px; font-size: 1.1666em; position: relative; } .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s:not(.ui-icon-triangle-1-s)::before { content: "\f106"; font-family: "FontAwesome"; position: ...

Sharing a virtualenv across several Python projects using Pipenv

There is a standard library for all projects in Python. However, several projects don’t always have the same dependencies all the time. That is where virtual environments come to play. You can follow this official document to use two separated tools virtualenv and pip to fulfill that need. My preferred alternative is to use pipenv . Pipenv is easy to use and convenient. The following are my steps to make a shared virtualenv for my all projects which requires the same dependencies. Step 1. Create an isolated virtualenv. python -m venv my-shared-env Step 2. Create a symbolic link to the created virtualenv. cd project_1 ln -s ~/.local/share/virtualenvs/my-shared-env .venv I have encountered the following issue at step 1. FileNotFoundError: [Errno 2] No such file or directory: '{my_project_path}/.venv/bin/pip': '{my_project_path}/.venv/bin/pip' The root cause was I tried to create virtualenv by running pipenv install and renaming the generated virtualenv to ...

How Would You Answer These Typical Interview Questions?

I have joined several job interviews with candidates at my current company. As a technical supporter, my attention was mainly focused on specific technical points rather than behavioral ones. However, I saw that these following typical questions were rarely missed for any interviews. In fact, there is a meaning behind of the questions. The concern is candidates should focus on answering the right things that interviewers really want to know. Take a look! Introduce about yourself It is "What and why are you fit for this job?". So, it is good to go "Talking too much about your hobbies."? I would say "We don't care about your hobbies much". ;) Why do you want to find a new job? It is "Why this job are interesting you?". So, it is good to go "Talking about something negative like 'I hate my boss/leader'"? I would say "Who wants to work with a negative person?" What did you do in your current j...

[Snippet] CSS - Child element overlap parent

I searched from somewhere and found that a lot of people says a basic concept for implementing this feature looks like below: HTML code: <div id="parent"> <div id="child"> </div> </div> And, CSS: #parent{ position: relative; overflow:hidden; } #child{ position: absolute; top: -1; right: -1px; } However, I had a lot of grand-parents in my case and the above code didn't work. Therefore, I needed an alternative. I presumed that my app uses Boostrap and AngularJs, maybe some CSS from them affects mine. I didn't know exactly the problem, but I believed when all CSS is loaded into my browser, I could completely handle it. www.tom-collinson.com I tried to create an example to investigated this problem by Fiddle . Accidentally, I just changed: position: parent; to position: static; for one of parents -> the problem is solved. Look at my code: <div class="modal-body dn-placeholder-parent-positi...

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