Christos Monogios

The previous days I had a great conversation about the fundamentals of JavaScript, scope, closure, etc.. The this keyword was also a discussion point. I wasn’t 100% sure of the rules that apply to this and I wanted to refresh my memory about the possible ways to use the keyword and for each case identify the owner of this when a function is invoked.

The four, and only four rules about this

• Using the new keyword for creating new objects. In that case the this will be bound to the new created object.

  As you can see in the following example, this binds to the object that created a new Car instance. For that reason we can have multiple objects from the same “class” (there are no classes in JavaScript) and each of these objects can have different values on their properties. An important thing to take away from this example is that we create a new property each time we use the this keyword inside the “constructor” function, and the value of this property is different for every instance the “class”.

Based on my current experience with the React Native framework, I would like to share with you some hints and tips that will improve your skills in the way you develop with the framework.

Isolate the business logic of your application from the UI/ components code

This is probably the most valuable information someone should have in her mind when developing with React Native. React Native tries to be as platform independent as possible, however, there will be cases, that you will have to write different JavaScript code for iOS and different code for Android.

You decided to create a new application for iOS and you want to program the app with the React Native framework.

Here is a list with all the steps you have to take if you want to start XCode Simulator and test the UI of your application on your developer machine:

JavaScript is a small language, however, as any other technology one should invest some time in learning the fundamentals of it, so that she has a solid knowledge when writing code or architecting web applications.

With the Must Know JavaScript features articles I try to give you a starting point for your further familiarization with the most important features of the language. You are going to use these features extensively as a JavaScript engineer, directly or indirectly.

Let’s talk about scope

In general, the scope in a programming language affects the visibility of fields/ properties in a class/ module or of the arguments passed or the variables declared inside a function. There are two main categories of scope in the modern languages:

• The block scope, where for example a variable is only visible inside an if condition or a for loop, when this variable is declared inside this condition. C# uses this type of scope.

• The function scope, where a variable is visible and can be used inside the whole function. The variable remains visible only inside the function and not outside of it.

The BadImageFormatException was unhandled – An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B) exception is being thrown when you try to load a .dll of your application which was compiled with 32 bits (X86) or 64 bits (X64) and the process that runs this file runs in a different bit-environment than the file.

If you see this exception when you run your C# unit tests in Visual Studio, then the reason for this error is that the test environment of Visual Studio has a different bit setting than the compiled code which is under test. To fix that you have to do the following change in your Visual Studio test settings: