Is "this" in JavaScript out of fashion?

Question

I'm not a frontend dev, but I recall that a few years ago, the this keyword was commonplace in frontend codebases.

In recent years, I haven't seen this get used anymore. In the last few frontend codebases I've worked on, I haven't seen it get invoked at all. Did it get obsoleted by recent developments in JavaScript, or is this just an idiosyncrasy of the developers I've been working with?

Answer 1

With the introduction of anonymous functions, binding this is generally not needed. In addition using frontend frameworks such as react or vue or angular or .... doesn't leave a room for needing to explicitly bind this; it is taken care of implicitly inside the framework implementation so you can write declarative code.

But it is not obsolete for many reasons:

In cases you need to use normal functions instead of anonymous functions (for hosting for ex) you may need to bind this.

Svelte for ex, requires a strong understanding of this, because you can use it in lifecycle methods and to reference custom components.

Finally the most common place where you would use this is in classes and utility JavaScript files.

Answer 2

As a C# developer I noticed there are two camps.

1. It is not required, not using it is shorter so we do not use it because we like to be concise.
2. It explicitly signals you are addressing a class member, not a local variable or argument or constant, hence it adds value to the code and prevents mistakes so we apply it consistently.

I am in the second camp, when it is up to me I consistently apply it. But I must say I do not miss it that much anymore now that the IDE tells me with colors that I am looking at a class member. I would say this is the main reason some people are no longer that anal about it.

So ultimately it is a matter of personal preference. I would have applauded it if it would have been mandatory, if the compiler/interpreter would just not accept references to class members without this. It now takes the local if it is there and falls back to a class member if there is no local, which is not a good thing for a programming language in my book.