Weird behavior of javaScript you should know!

Abhinav Kale — Mon, 10 Jan 2022 15:53:26 +0000

We know that javaScript sometimes behaves weird as compare to other programming languages, but initially it was design only to make web pages.

But now in today's world, we can do so many things using javaScript with help of other libraries/framework like react, angular.

This weird behaviour is not a fault of javaScript, this is how the language was design in the initial phase. So we should understand why this behaviour happens, so we can take primitive actions based on it.(If we are intending that this should not happen)

So here, we make one object calling its name weirdObject which has property obj_id and obj_name which is further divided into an object which has property obj_title and type.

If we run our code with node we get the output as the object considering obj_id and obj_name.

Now, if we want to change the obj_id of the object we can do that in javaScript inspite of using const keyword.(It is allowed to change inside property of javaScript whether we use const or not)

To change this behaviour, we can use Object.freeze() method which freezes an object.

Here the value of obj_id not changed. A frozen object can no longer be changed; freezing an object prevents new properties from being added to it, existing properties from being removed, prevents changing the enumerability, configurability, and writability of existing properties, and also prevents the values of existing properties from being changed.

But, what if we want to change value of the obj_title from "My Object" to "This Object" which is present inside obj_name object of weirdObject after using Object.freeze() method.

Let's see..

Yes, we can do that..!! This is called Shallow freeze which only applies to the immediate properties of the object itself and will prevent future property addition, removal or value re-assignment operations only on object. If the value of those properties are objects themselves, those objects are not frozen and may be the target of property addition, removal or value re-assignment operations.

To make object immutable, we will have to add explicit function which will check is wheather the object has another object present inside it.

Hope this odd behaviour of javaScript information helps you.
Thanks for reading and happy coding!

Do you know Isomorphic JavaScript?

Abhinav Kale — Thu, 12 Aug 2021 14:21:56 +0000

In programming we tend to hear a lot of really strange words such as isomorphism, etc.

What is Isomorphic?

In general term "iso" means "same" and "morphic" means "form" ie same form that we are studied from our childhood.

In simplest terms isomorphic javaScript is the javaScript that can be run on both the server as well as on the client.

Let's discuss with examples below.

This code snippet is isomorphic, the code will run in a
node.js environment and it will also run in the web browser.

This code doesn't uses any node-specific libraries or browse any web apis, it's just an arrow function in javaScript that will run in environment.

Now let's have a look on another example which is not isomorphic.
We will be using fetch api to get some data from external api(NewsAPI).

This code is not isomorphic because the fetch function is provided by the web browser and results in ReferenceError.

If we want to run on both the client and the server we have to import a third-party library such as axios. The code something looks like this

This would be considered as isomorphic javaScript but it's important to note that we only need one successful path that will run on both the server and the client in order to be considered isomorphic.

If we have a javaScript function that checks the environment to determine whether or not it's on the client or the server and then it has the path for both of those cases then that can be considered as isomorphic javaScript for example this

This code checks for the window object and determines whether or not it is running on the client or the server and then logs the result.

This is isomorphic because it will run on both the server and the client so it's important to note here that isomorphic javaScript is the way that we write the code and
it's "not a particular technology" it's just sort of like a design pattern. Writing code in this way allows you to be able to do certain unique things such as server side rendering.

Hope this information helps you to understand isomorphic javaScript.
Thanks for reading and happy coding!

DEV Community: Abhinav Kale

Weird behavior of javaScript you should know!

Do you know Isomorphic JavaScript?

What is Isomorphic?