JavaScript Best Practices — Generators and Object Properties

JavaScript is a very forgiving language. It’s easy to write code that runs but has mistakes in it.
In this article, we’ll look at the best practices when using generators and defining and using object properties.
Don’t Use Generators If We Want To Transpile to ES5
Generator code doesn’t transpile well to ES5 code, so we may want to think twice if we’re targeting our build artifact to build into ES5 code.
However, this shouldn’t be the case with modern transpilers since they create custom closure based state machines from generators and async functions. They work the same way. However, the only advantage is that the transpile code is harder to debug even with source maps.
Therefore, if we never have to debug the transpiled code, then we can go ahead and use generators. Otherwise, we should think twice before using them in our code.

#programming #web-development #javascript

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JavaScript Best Practices — Generators and Object Properties
Arvel  Parker

Arvel Parker


How to Find Ulimit For user on Linux

How can I find the correct ulimit values for a user account or process on Linux systems?

For proper operation, we must ensure that the correct ulimit values set after installing various software. The Linux system provides means of restricting the number of resources that can be used. Limits set for each Linux user account. However, system limits are applied separately to each process that is running for that user too. For example, if certain thresholds are too low, the system might not be able to server web pages using Nginx/Apache or PHP/Python app. System resource limits viewed or set with the NA command. Let us see how to use the ulimit that provides control over the resources available to the shell and processes.

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MEAN Stack Tutorial MongoDB ExpressJS AngularJS NodeJS

We are going to build a full stack Todo App using the MEAN (MongoDB, ExpressJS, AngularJS and NodeJS). This is the last part of three-post series tutorial.

MEAN Stack tutorial series:

AngularJS tutorial for beginners (Part I)
Creating RESTful APIs with NodeJS and MongoDB Tutorial (Part II)
MEAN Stack Tutorial: MongoDB, ExpressJS, AngularJS and NodeJS (Part III) 👈 you are here
Before completing the app, let’s cover some background about the this stack. If you rather jump to the hands-on part click here to get started.

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Brain  Crist

Brain Crist


Docker Applikationen mit Visual Studio Code debuggen

Mit dem integrierten Debugger von Visual Studio Code lassen sich ASP.NET Core bzw. .NET Core Applikationen einfach und problemlos debuggen. Der Debugger unterstützt auch Remote Debugging, somit lassen sich zum Beispiel .NET Core Programme, die in einem Docker-Container laufen, debuggen.

Als Beispiel Applikation reicht das Default-Template für MVC Applikationen dotnet new mvc

$ md docker-core-debugger
$ cd docker-core-debugger
$ dotnet new mvc

Mit dotnet run prüfen wir kurz, ob die Applikation läuft und unter der Adresse http://localhost:5000 erreichbar ist.

$ dotnet run
$ Hosting environment: Production
$ Content root path: D:\Temp\docker-aspnetcore
$ Now listening on: http://localhost:5000

Die .NET Core Applikation builden wir mit dotnet build und publishen alles mit Hilfe von dotnet publish

$ dotnet build
$ dotnet publish -c Debug -o out --runtime linux-x64

Dabei gilt es zu beachten, dass die Build Configuration mit -c Debug gesetzt ist und das Output Directory auf -o out. Sonst findet Docker die nötigen Binaries nicht. Für den Docker Container brauchen wir nun ein Dockerfile, dass beim Start vorgängig den .NET Core command line debugger (VSDBG) installiert. Das Installations-Script für VSDBG ist unter abfrufbar.

FROM microsoft/aspnetcore:latest

RUN apt-get update \
    && apt-get install -y --no-install-recommends \
       unzip procps \
    && rm -rf /var/lib/apt/lists/* \
    && curl -sSL | bash /dev/stdin -v latest -l /vsdbg

COPY ./out .
ENTRYPOINT ["dotnet", "docker-core-debugger.dll"]

Den Docker Container erstellen wir mit dem docker build Kommando

$ docker build -t coreapp .

und starten die Applikation mit docker run.

$ docker run -d -p 8080:80 --name coreapp coreapp

Jetzt muss Visual Studio Code nur noch wissen, wo unsere Applikation läuft. Dazu definieren wir eine launch.json vom Typ attach und konfigurieren die nötigen Parameter für den Debugger.

    "version": "0.2.0",
    "configurations": [
            "name": ".NET Core Remote Attach",
            "type": "coreclr",
            "request": "attach",
            "processId": "${command:pickRemoteProcess}",
            "pipeTransport": {
                "pipeProgram": "docker",
                "pipeArgs": ["exec", "-i coreapp ${debuggerCommand}"],
                "quoteArgs": false,
                "debuggerPath": "/vsdbg/vsdbg",
                "pipeCwd": "${workspaceRoot}"

            "logging": {
                "engineLogging": true,
                "exceptions": true,
                "moduleLoad": true,
                "programOutput": true

Mit F5 starten wir den Debugger. Wenn alles klappt, sollte eine Auswahl der Prozesse des Docker-Containers sichtbar sein.


Nun muss der dotnet Prozess ausgewählt werden. Der Visual Studio Code Debugger verbindet sich darauf mit VSDBG und wir können wie gewohnt unseren Code debuggen. Dazu setzen wir einen Breakpoint in der Index-Action des HomeControllers und rufen mit dem Browser die URL http://localhost:8080/ auf.


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Tyrique  Littel

Tyrique Littel



When I install s3cmd package on my FreeBSD system and try to use the s3cmd command I get the following error:

_ERROR: Test failed: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (ssl.c:1091)

How do I fix this problem on FreeBSD Unix system?

Amazon Simple Storage Service (s3 ) is object storage through a web service interface or API. You can store all sorts of files. FreeBSD is free and open-source operating systems. s3cmd is a command-line utility for the Unix-like system to upload, download files to AWS S3 service from the command line.

ERROR: Test failed: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed error and solution

This error indicates that you don’t have packages correctly installed, especially SSL certificates. Let us see how to fix this problem and install s3cmd correctly on FreeBSD to get rid of the problem.

How to install s3cmd on FreeBSD

Search for s3cmd package:

$ pkg search s3cmd

Execute the following command and make sure you install Python 3.x package as Python 2 will be removed after 2020:

$ sudo pkg install py37-s3cmd-2.1.0

Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
All repositories are up to date.
Checking integrity... done (0 conflicting)
The following 8 package(s) will be affected (of 0 checked):

New packages to be INSTALLED:
	libffi: 3.2.1_3
	py37-dateutil: 2.8.1
	py37-magic: 5.38
	py37-s3cmd: 2.1.0
	py37-setuptools: 44.0.0
	py37-six: 1.14.0
	python37: 3.7.8
	readline: 8.0.4

Number of packages to be installed: 8

The process will require 118 MiB more space.

Proceed with this action? [y/N]: y
[rsnapshot] [1/8] Installing readline-8.0.4...
[rsnapshot] [1/8] Extracting readline-8.0.4: 100%
[rsnapshot] [2/8] Installing libffi-3.2.1_3...
[rsnapshot] [8/8] Extracting py37-s3cmd-2.1.0: 100%
Message from python37-3.7.8:

Note that some standard Python modules are provided as separate ports
as they require additional dependencies. They are available as:

py37-gdbm       databases/py-gdbm@py37
py37-sqlite3    databases/py-sqlite3@py37
py37-tkinter    x11-toolkits/py-tkinter@py37

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Creating RESTful APIs with NodeJS and MongoDB Tutorial

Welcome to this tutorial about RESTful API using Node.js (Express.js) and MongoDB (mongoose)! We are going to learn how to install and use each component individually and then proceed to create a RESTful API.

MEAN Stack tutorial series:

AngularJS tutorial for beginners (Part I)
Creating RESTful APIs with NodeJS and MongoDB Tutorial (Part II) 👈 you are here
MEAN Stack Tutorial: MongoDB, ExpressJS, AngularJS and NodeJS (Part III)

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