Hello there, welcome to my first technical weblog submit! That is the beginning of a collection the place I clarify ideas associated to OOP (Object Oriented Programming) with JavaScript. In case you don’t know what any of these phrases imply, that’s okay, however you should definitely learn by way of the subsequent paragraph and examine the free assets linked inside to get a primer earlier than studying the remainder of the submit! In case you’re acquainted already, be happy to skip the subsequent part.



A fast primer

OOP is a programming paradigm, or a mind-set about programming. On this mind-set, web sites and functions are constructed round objects.

In JavaScript, objects are variables that act as containers for knowledge. Objects seem as a group of key:worth pairs like this instance under:

a screenshot of an object written in JavaScript with labels “keys” & “values”.

Take a look at this useful resource for extra on what OOP is & how it’s used: https://www.techtarget.com/searchapparchitecture/definition/object-oriented-programming-OOP



“this”

You’ll have encountered the phrase “this” whereas studying JavaScript code. In case you’re like me, you had been most likely tremendous confused on the phrase and its which means. “this” is a relative reference to the thing it belongs to. The key phrase makes your code extra reusable and could be very helpful to be taught!

As somebody who loves languages and writing, viewing the technical time period “this” in the identical manner I take into consideration pronouns in English actually helped me wrap my thoughts round it. I’d wish to share my comparability simply in case it is usually useful to you!

In English, generally we are saying “she” or “it” or “this” to consult with one thing else. For instance, in case your dad and mom let you know “clear up this room”, you already know precisely what room they’re referring to based mostly on the dialog’s context. In the event that they’re standing in the lounge once they say it, this refers to the lounge. In the event that they’re standing in your bed room, this refers to your bed room. In the identical manner, “this” in programming may have completely different meanings relying on context:

Alone, this refers to one thing known as the “international object.”

To do this out, open your browser’s console and simply sort in

console.log(this);

screenshot of a terminal with console output that says

It is best to see that this === window! Window is the global context of your browser.

In a operate, this ⇒ international object*.

In an occasion, this ⇒ the ingredient that acquired the occasion*.

*There are some exceptions right here! MDN has an important breakdown of how one can derive the which means of “this” in numerous eventualities:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this



constructors & the “new” key phrase

Constructors are capabilities that create new objects. They outline properties and behaviors that can belong to that object. Consider them as a blueprint! Many real-world objects are created from blueprints. All automobiles, for instance, are likely to share a set of widespread properties and conduct. They’ve wheels, home windows, and the flexibility to drive.

A constructor for a Vehicles object would appear to be this:

screenshot of a code snippet written in JavaScript.

What makes constructors cool is the truth that you should use the properties and behaviors outlined inside them to create a number of “variations” (or in programming phrases, “cases) of the identical object.

This may be achieved when the new operator is used when calling a constructor. This phrase tells JavaScript to create a brand new occasion of an object. (By the best way, any time an object is created it’s instantiated.) The brand new key phrase is essential as a result of with out it, the this contained in the constructor wouldn’t level to the newly created object. new tells this what context it ought to consult with.

two screenshots - one of a JavaScript code snippet, the other of a terminal showing console output.

Now your new object can have all of the properties outlined within your constructor, yay!



utilizing parameters for extra flexibility:

You possibly can enable your constructor to just accept parameters to extra simply change its properties to completely different values.

Let’s say we’ve got a constructor operate known as Programmer, which takes in two arguments “title” and “language” and has three properties outlined:

two screenshots - one of a JavaScript code snippet, the other of a terminal showing console output.

With parameters, you can also make your objects extra versatile!

I hope this weblog submit has helped make clear this, constructors, and the “new” key phrase for you! That is my first time making an attempt to elucidate a technical idea, so I welcome all some suggestions. Let me know what you assume by sharing this submit on Twitter! In case you’d like me to make this a collection the place I cowl among the key ideas of OOP, let me know. I’d love to jot down extra in regards to the prototype chain & inheritance particularly if it might be precious.
To learn extra of my blogs, try my web site Code Newbie Chronicles!

Thanks a lot for studying!

Ebony

(Disclaimer: this submit is just not a complete technical clarification of those ideas. As I be taught extra, I’ll you should definitely re-visit this submit and proper any inaccuracies!)

One other free useful resource on OOP:

https://javascriptissexy.com/oop-in-javascript-what-you-need-to-know/#:~:text=JavaScript Prototype,languages and Functions in JavaScript.





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