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Articles by Gerd Wagner (Articles: 15, Technical Blogs: 27, Tip/Tricks: 2)

Articles: 15, Technical Blogs: 27, Tip/Tricks: 2

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Average article rating: 4.84

3 Apr 2014   Updated: 28 Nov 2015   Rating: 4.73/5    Votes: 15   Popularity: 5.56
Licence: CPOL    Views: 41,530     Bookmarked: 24   Downloaded: 0
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What are the most important types of integrity constraints to be checked in any data management app?
Internet of Things
10 Dec 2014   Updated: 10 Dec 2014   Rating: 5.00/5    Votes: 6   Popularity: 3.89
Licence: CPOL    Views: 16,980     Bookmarked: 9   Downloaded: 0
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In this article, we describe how to develop IoT apps with Node/JavaScript for the Arduino-compatible PCDuino. We take JavaScript to the land of microseconds where a digitalWrite operation takes 6-7 microseconds and a digitalRead operation takes 4-5 microseconds.
Arduino
28 Jul 2015   Updated: 28 Jul 2015   Rating: 4.88/5    Votes: 15   Popularity: 5.73
Licence: CPOL    Views: 49,919     Bookmarked: 14   Downloaded: 0
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When working with embedded devices, RAM (random access memory) is one of the most valuable and limited resource of the system. The focus of this article is on the RAM usage optimization for Arduino MCUs, but the same principle applies to many other embedded devices.
Programming Languages
Javascript
2 Jul 2015   Updated: 25 Jul 2016   Rating: 4.96/5    Votes: 126   Popularity: 10.38
Licence: CPOL    Views: 164,565     Bookmarked: 191   Downloaded: 0
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A short summary of JavaScript's main features, including a discussion of the different kinds of JS objects, basic data structures, functions as first class citizens, and code patterns for implementing classes. "In over 20 years programming this is the single best overview of any language ever!"
14 May 2019   Updated: 14 May 2019   Rating: 5.00/5    Votes: 1   Popularity: 0.00
Licence: CPOL    Views: 5,973     Bookmarked: 5   Downloaded: 0
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We show how to deal with key-value pairs and how to manage a key-value store using JavaScript's localStorage API.
Web Development
ASP.NET
26 Feb 2015   Updated: 6 Apr 2015   Rating: 4.92/5    Votes: 22   Popularity: 6.40
Licence: CPOL    Views: 34,321     Bookmarked: 41   Downloaded: 0
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This is an alternative for "Understanding Association, Aggregation, and Composition", correcting three flaws, one in each of the three explanations, contained in the original article.
HTML
21 May 2015   Updated: 2 Jul 2015   Rating: 4.55/5    Votes: 8   Popularity: 4.10
Licence: CPOL    Views: 23,761     Bookmarked: 16   Downloaded: 191
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This tutorial shows how to build a plain JS web app where model classes have enumeration attributes, which have to be rendered in the HTML user interface with selection lists, radio button groups and checkbox groups.
9 Sep 2015   Updated: 9 Sep 2015   Rating: 5.00/5    Votes: 13   Popularity: 5.57
Licence: CPOL    Views: 37,850     Bookmarked: 28   Downloaded: 291
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Learn how to build a front-end web application with minimal effort in seven steps, using the AngularJS framework and the cloud storage service Parse.com.
2 Apr 2014   Updated: 1 Dec 2015   Rating: 4.87/5    Votes: 53   Popularity: 8.36
Licence: CPOL    Views: 352,762     Bookmarked: 120   Downloaded: 5,532
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Learn how to build a front-end web application in plain JavaScript with minimal effort. Do not use any (third-party) framework or library, such as jQuery or Angular, which create black-box dependencies and overhead, and prevent you from learning how to do it yourself.
29 Dec 2015   Updated: 18 Jan 2016   Rating: 4.43/5    Votes: 4   Popularity: 2.67
Licence: CPOL    Views: 22,041     Bookmarked: 1   Downloaded: 52
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cLASSjs is a small (2 kB) JS library for defining constructor-based classes with prototype-based method inheritance like so: Student = new cLASS({ Name:"Student", supertypeName:"Person", properties:..., methods:...}).
25 Feb 2015   Updated: 23 Mar 2015   Rating: 4.53/5    Votes: 9   Popularity: 4.32
Licence: CPOL    Views: 18,502     Bookmarked: 12   Downloaded: 169
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Learn how to develop front-end web apps with unidirectional associations between model classes, such as the associations that assign authors and publishers to books. While in many other tutorials, associations are only superficially discussed, if at all, this article provides an in-depth explanation
10 Apr 2014   Updated: 25 Jun 2015   Rating: 4.89/5    Votes: 18   Popularity: 6.01
Licence: CPOL    Views: 46,905     Bookmarked: 46   Downloaded: 689
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Learn how to develop front-end web apps with responsive (HTML5) constraint validation using plain JavaScript. Do not use any framework/library (like jQuery or Angular), which just create black-box dependencies and overhead, and prevent you from learning how to do it yourself.
27 Oct 2014   Updated: 24 Aug 2016   Rating: 4.94/5    Votes: 7   Popularity: 4.17
Licence: CPOL    Views: 21,531     Bookmarked: 8   Downloaded: 105
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Avoiding boilerplate code for constraint validation in a JavaScript front-end web app by using the model-based framework mODELcLASSjs
22 Jan 2016   Updated: 21 Dec 2016   Rating: 4.95/5    Votes: 38   Popularity: 7.71
Licence: CPOL    Views: 268,589     Bookmarked: 57   Downloaded: 10,523
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WebRTC (Web Real Time Communication) is a new web standard that allows peer-to-peer communication between browsers for high-quality RTC apps. In our tutorial, we show how to use it for building a video chat app.
19 Nov 2015   Updated: 20 Nov 2015   Rating: 5.00/5    Votes: 10   Popularity: 4.77
Licence: CPOL    Views: 170,637     Bookmarked: 20   Downloaded: 1,666
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Learn how to build a Java back-end web application with minimal effort, using Java Server Faces (JSF) as the user interface technology, the Java Persistence API (JPA) for object-to-storage mapping, and a MySQL database.

Average blogs rating: 4.74

21 Nov 2014   Updated: 6 Apr 2015   Rating: 4.75/5    Votes: 5   Popularity: 3.32
Licence: CPOL    Views: 14,080     Bookmarked: 11   Downloaded: 0
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Why are associations so difficult to understand, not just for developers?
24 Aug 2016   Updated: 2 Sep 2016   Rating: 4.72/5    Votes: 9   Popularity: 4.51
Licence: CPOL    Views: 14,680     Bookmarked: 11   Downloaded: 0
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We discuss the widely used, but ill-defined MVC architecture metaphor, and point out that the model classes should be decoupled from the storage component.
All Topics
1 Oct 2015   Updated: 1 Oct 2015   Rating: 4.21/5    Votes: 8   Popularity: 3.81
Licence: CPOL    Views: 4,591     Bookmarked: 6   Downloaded: 0
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If you want to become a great app developer, it's not sufficient that you master your favorite programming technologies. It's essential that you understand all basic concepts and techniques, not just in programming, but also in information management.
Database Development
20 Jan 2015   Updated: 20 Jan 2015   Rating: 4.89/5    Votes: 8   Popularity: 4.42
Licence: CPOL    Views: 24,220     Bookmarked: 14   Downloaded: 0
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Storing database tables in JavaScript's Local Storage
24 Jan 2018   Updated: 24 Jan 2018   Rating: 5.00/5    Votes: 2   Popularity: 1.51
Licence: CPOL    Views: 11,031     Bookmarked: 8   Downloaded: 0
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How to create and clear an IndexedDB database keeping all code in a single HTML file. Creating an IndexedDB database means first creating an empty database, and then adding records to its empty tables (or "object stores").
Internet of Things
17 Apr 2016   Updated: 18 Apr 2016   Rating: 5.00/5    Votes: 12   Popularity: 5.40
Licence: CPOL    Views: 28,186     Bookmarked: 19   Downloaded: 288
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Learn how to develop Arduino-based apps for the Web of Things (WoT). This second part of a series of tutorials shows how to read analog and digital sensors with the help of Arduino.
7 Apr 2016   Updated: 22 Apr 2016   Rating: 4.80/5    Votes: 23   Popularity: 6.54
Licence: CPOL    Views: 46,953     Bookmarked: 40   Downloaded: 296
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Learn how to develop Arduino-based apps for the Web of Things (WoT). This first part of a series of tutorials shows the basics of an Arduino program (known as a "sketch") and provides a quick introduction to some electronic components, including resistors, RGB LEDs and LEDs in general.
14 Oct 2015   Updated: 30 Dec 2015   Rating: 4.60/5    Votes: 4   Popularity: 2.77
Licence: CPOL    Views: 18,543     Bookmarked: 13   Downloaded: 0
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Architectures for the Web of Things
Arduino
23 Jul 2015   Updated: 23 Jul 2015   Rating: 4.60/5    Votes: 9   Popularity: 4.39
Licence: CPOL    Views: 103,348     Bookmarked: 13   Downloaded: 0
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Three easy ways to programmatically reboot/reset an Arduino MCU.
4 Dec 2016   Updated: 4 Dec 2016   Rating: 5.00/5    Votes: 7   Popularity: 4.23
Licence: CPOL    Views: 20,601     Bookmarked: 15   Downloaded: 482
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Home Automation is made simple for everyone, with the industrial grade PRODINo ESP8266 based module. It can be programmed with the Arduino IDE and allows to control (ON/OFF switch) mains (110-240 VAC) powered devices such as light bulbs, water pumps, cafe machines or garage doors.
22 Jul 2015   Updated: 22 Jul 2015   Rating: 4.60/5    Votes: 5   Popularity: 3.22
Licence: CPOL    Views: 9,040     Bookmarked: 6   Downloaded: 0
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Learn how to identifying the Arduino microcontroller type by simply using C/C++ code.
Raspberry-Pi
14 Oct 2016   Updated: 20 Oct 2016   Rating: 4.48/5    Votes: 8   Popularity: 4.04
Licence: CPOL    Views: 50,996     Bookmarked: 19   Downloaded: 340
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As opposed to the less powerful Arduino, the competitively priced and WiFi-enabled ESP8266 supports the Web-of-Things (WoT) since it can be programmed in JavaScript.
Programming Languages
C
3 May 2016   Updated: 3 May 2016   Rating: 5.00/5    Votes: 11   Popularity: 5.21
Licence: CPOL    Views: 27,592     Bookmarked: 15   Downloaded: 358
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In this multi-part tutorial we show how to develop Arduino-based apps for the Web of Things (WoT). This third part shows how to set up a connection between an Arduino and the Internet via a WiFi network and use HTTP(S) to send data to a free cloud service like ThingSpeak.
ECMAScript 6
24 May 2017   Updated: 24 May 2017   Rating: 5.00/5    Votes: 3   Popularity: 2.39
Licence: CPOL    Views: 7,881     Bookmarked: 3   Downloaded: 0
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Already available from ES5.1 (and even supported by IE 9), JavaScript's set and get methods have not been used very widely. Their main use case is the implementation of a best practice in OOP.
Javascript
11 Feb 2015   Updated: 11 Feb 2015   Rating: 5.00/5    Votes: 1   Popularity: 0.00
Licence: CPOL    Views: 8,990     Bookmarked: 2   Downloaded: 0
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AngularJS does not have a Model: It's not MV*, But rather VM*
16 Jul 2015   Updated: 16 Jul 2015   Rating: 5.00/5    Votes: 1   Popularity: 0.00
Licence: CPOL    Views: 7,191     Bookmarked: 2   Downloaded: 0
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The concept of a class is fundamental in object-oriented programming. Objects instantiate (or are classified by) a class. A class defines the properties and methods (as a blueprint) for the objects that instantiate it.
29 Jan 2015   Updated: 29 Jan 2015   Rating: 4.60/5    Votes: 3   Popularity: 2.19
Licence: CPOL    Views: 10,640     Bookmarked: 3   Downloaded: 0
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Using the HTML5 element allows to express a human-readable date or a timestamp in a web page, and annotate it with a machine-readable date/time value that can be extracted and processed by applications.
6 Jul 2021   Updated: 6 Jul 2021   Rating: 5.00/5    Votes: 2   Popularity: 1.51
Licence: CPOL    Views: 5,091     Bookmarked: 4   Downloaded: 0
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The evolution of asynchronous programming in JavaScript: callbacks, promises, async/await
UML
16 Aug 2017   Updated: 16 Aug 2017   Rating: 0.00/5    Votes: 0   Popularity: 0.00
Licence: CPOL    Views: 5,562     Bookmarked: 1   Downloaded: 0
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How to represent information models as RDF and OWL vocabularies, and how to embed simple meta-data statements (annotations) in web documents.
Reactive
18 Jul 2016   Updated: 18 Jul 2016   Rating: 5.00/5    Votes: 1   Popularity: 0.00
Licence: CPOL    Views: 7,842     Bookmarked: 2   Downloaded: 0
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Reactive programming and how it works
Structures
4 Mar 2015   Updated: 4 Mar 2015   Rating: 4.00/5    Votes: 8   Popularity: 3.61
Licence: CPOL    Views: 9,073     Bookmarked: 2   Downloaded: 0
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The four types of basic data structures supported by JavaScript are: array lists, maps, records and JSON tables.
Web Development
18 Feb 2015   Updated: 18 Feb 2015   Rating: 4.90/5    Votes: 6   Popularity: 3.81
Licence: CPOL    Views: 17,192     Bookmarked: 4   Downloaded: 0
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Enumerations and Enumeration Attributes in JavaScript
17 Nov 2014   Updated: 17 Nov 2014   Rating: 4.33/5    Votes: 2   Popularity: 1.30
Licence: CPOL    Views: 10,561     Bookmarked: 2   Downloaded: 0
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Difference between a JavaScript object and a UML/Java object
HTML
17 Feb 2016   Updated: 31 Jan 2017   Rating: 5.00/5    Votes: 9   Popularity: 4.77
Licence: CPOL    Views: 14,601     Bookmarked: 12   Downloaded: 95
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While many new JavaScript features of ES6 (=ES2015) are still (in 2016!) not available in all important web browsers, the promising new feature of a JavaScript "promise" has arrived. This tutorial shows how to use it.
24 Apr 2020   Updated: 24 Apr 2020   Rating: 5.00/5    Votes: 4   Popularity: 3.01
Licence: CPOL    Views: 6,730     Bookmarked: 6   Downloaded: 0
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The most important new language elements of JavaScript for basic programming
6 Oct 2015   Updated: 6 Oct 2015   Rating: 3.63/5    Votes: 8   Popularity: 3.28
Licence: CPOL    Views: 24,391     Bookmarked: 6   Downloaded: 0
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The proper way of creating an HTML table with JavaScript and inserting it into the HTML body element is using the DOM methods insertRow and insertCell.
HTML5
25 Oct 2017   Updated: 25 Oct 2017   Rating: 5.00/5    Votes: 6   Popularity: 3.89
Licence: CPOL    Views: 11,292     Bookmarked: 3   Downloaded: 0
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The HTML specification defines an event-based drag-and-drop (D&D) mechanism, which is supported by all current major browsers (including IE11 and iOS/Safari), except on Android. We show the minimum setup for a working D&D operation.

Average tips rating: 5.00

Programming Languages
Javascript
10 Dec 2015   Updated: 10 Dec 2015   Rating: 5.00/5    Votes: 5   Popularity: 3.49
Licence: CPOL    Views: 7,810     Bookmarked: 4   Downloaded: 0
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Don't confuse a DOM collection with a JS array: Array functions, such as the forEach looping method, cannot be applied to a DOM collection!
12 Jul 2018   Updated: 12 Jul 2018   Rating: 5.00/5    Votes: 1   Popularity: 0.00
Licence: CPOL    Views: 4,810     Bookmarked: 1   Downloaded: 0
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How to drop a DOM node without consulting its parent

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Instructor / Trainer
Germany Germany
Researcher, developer, instructor and cat lover.

Co-Founder of web-engineering.info and the educational simulation website sim4edu.com.