Whether you’re a C# (or similar language like Java) developer eager to learn JavaScript or you’ve already been working with JS for some time, I hope you find this article interesting. I collected for you 10 JavaScript features which are/were the most shocking for C# developers who learnt JavaScript.
These features of JavaScript language are the most striking differences compared to C# ecosystem. If you’re about to learn JavaScript, sooner or later you’ll also have to deal with them.
Before we begin, one disclaimer: the goal of this post isn’t stating which language is better or worse. JavaScript and C# are different programming languages and their use cases are also completely different. One is better for some usages, while the other is better for others. The list is my and other readers’ subjective one and you don’t need to agree with all points. I’m myself a C# developer on my JavaScript learning journey, so I’d like to help you grasping these confusing concepts 😉
1. Dynamic Typing
Obviously, the first difference JavaScript newbie notices is that the language is dynamically-typed. It means that the types (of variables, functions, actually of almost everything) are checked at runtime, not at compile time like in C# or Java. Because of that, there’s not much difference in defining variables and assigning them data of various data types: .gist table { margin-bottom: 0; } JavaScript’s variables are not associated with any particular data type. That’s why it’s completely legit to write something like that: .gist table { margin-bottom: 0; } Because JavaScript is dynamically-typed, issues with types are detected at runtime (e.g. error is thrown as soon as you try to use a variable in a context which expects another data type), not during compilation time as it would be in C# or Java. If you have some experience with statically-typed languages, you may now feel how much confusion and troubles dynamic typing can bring. At least at the beginning.2. Implicit types coercion
JavaScript has one more interesting feature – types coercion. Even though this term’s name sounds a bit weird 🙂, it’s quite simple: types coercion happens when a value of one type is converted to another one. It may be explicit, but harder to grasp is the implicit types coercion. It means that developer doesn’t necessarily ask for converting value of some type to another, but it still happens “silently”. To visualize it, consider the following code: .gist table { margin-bottom: 0; } Even though console.log() expects data of text type, isGreatDeveloper which holds a boolean value at the moment is implicitly converted to text. The above example was just to show you what types coercion is all about, but it gets more confusing in reality. First misleading concept is that JS has actually two equality operators: == and ===. Let’s see some code example to know the difference between them: .gist table { margin-bottom: 0; } The first == operator performs an implicit types coercion before performing the actual comparison. That’s why the text ’26’ is “silently” converted to a number 26 and the if statement is true at this point. Because of that, we should normally always use === operator to avoid such unclear situations. Existence of such (and many more) nice concepts of JavaScript leads to finding such interesting Tweets:*shuts laptop forever* pic.twitter.com/3GS1JfNDSP
