One of the first things to understand in JavaScript — Immutability

Let us go back to basics: “In JavaScript, are variables or constants immutable?”

The answer is neither, and if you even have a little hesitation on your answer, read on. Every programming language have different flavors and characteristics, and in JavaScript, this is one of the most important things to be aware of, especially while we are picking up a few languages like Python, Java, etc.

You may not necessarily change how you code in JavaScript immediately, but in knowing this early, it will prevent you from getting into nasty situations that are difficult to debug later on. I will include some ways you can adopt to prevent getting into such problems as well — different ways to do shallow & deep copy.

Just a quick summary before we begin:

Variables (initialised with let) — Re-assignable & Mutable

Constants (initialised with const) — Non re-assignable & Mutable

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Before we explain mutability in JavaScript, let us quickly go through some basics… You may skip this part.

There are broadly a few groups of data types in JavaScript:

1. Primitive (primary)— Boolean, Number, String
2. Non-primitive (reference) or Objects — Object, Array, Function
3. Special— Null, Undefined

Quick tip, you can use _console.log(typeof unknownVar)_ to figure out the data type of the variable you are dealing with

Primitive data types are Immutable by default

For primitive data types (like boolean, number and strings), they are **immutable **if they are declared as constants because for these data types, you cannot add any additional properties or mutate certain properties.

To ‘change/alter’ primitives, it simply means you have to reassign them, which is only possible if they are declared as variables.

let var1 = 'apple' //'apple' is stored in memory location A
var1 = 'orange' //'orange' is stored in memory location B

const var2 = 'apple'
var2 = 'orange' // ERROR: Re-assignment not allowed for constants

In the example above, if we edit the string for var1, JavaScript will simply create another string at another memory location and var1 will point to this new memory location, and this is called Re-assignment. This applies for all _primitive data types _regardless if they are declared as variables or constants.

And all constants cannot be re-assigned.

#javascript #programming #es6 #web-development #immutability

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One of the first things to understand in JavaScript — Immutability

Let us go back to basics: “In JavaScript, are variables or constants immutable?”

The answer is neither, and if you even have a little hesitation on your answer, read on. Every programming language have different flavors and characteristics, and in JavaScript, this is one of the most important things to be aware of, especially while we are picking up a few languages like Python, Java, etc.

You may not necessarily change how you code in JavaScript immediately, but in knowing this early, it will prevent you from getting into nasty situations that are difficult to debug later on. I will include some ways you can adopt to prevent getting into such problems as well — different ways to do shallow & deep copy.

Just a quick summary before we begin:

Variables (initialised with let) — Re-assignable & Mutable

Constants (initialised with const) — Non re-assignable & Mutable

---

Before we explain mutability in JavaScript, let us quickly go through some basics… You may skip this part.

There are broadly a few groups of data types in JavaScript:

1. Primitive (primary)— Boolean, Number, String
2. Non-primitive (reference) or Objects — Object, Array, Function
3. Special— Null, Undefined

Quick tip, you can use _console.log(typeof unknownVar)_ to figure out the data type of the variable you are dealing with

Primitive data types are Immutable by default

For primitive data types (like boolean, number and strings), they are **immutable **if they are declared as constants because for these data types, you cannot add any additional properties or mutate certain properties.

To ‘change/alter’ primitives, it simply means you have to reassign them, which is only possible if they are declared as variables.

let var1 = 'apple' //'apple' is stored in memory location A
var1 = 'orange' //'orange' is stored in memory location B

const var2 = 'apple'
var2 = 'orange' // ERROR: Re-assignment not allowed for constants

In the example above, if we edit the string for var1, JavaScript will simply create another string at another memory location and var1 will point to this new memory location, and this is called Re-assignment. This applies for all _primitive data types _regardless if they are declared as variables or constants.

And all constants cannot be re-assigned.

#javascript #programming #es6 #web-development #immutability

The essential JavaScript concepts that you should understand

As a JavaScript developer of any level, you need to understand its foundational concepts and some of the new ideas that help us developing code. In this article, we are going to review 16 basic concepts. So without further ado, let’s get to it.

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What is JavaScript - Stackfindover - Blog

Who invented JavaScript, how it works, as we have given information about Programming language in our previous article ( What is PHP ), but today we will talk about what is JavaScript, why JavaScript is used The Answers to all such questions and much other information about JavaScript, you are going to get here today. Hope this information will work for you.

Who invented JavaScript?

JavaScript language was invented by Brendan Eich in 1995. JavaScript is inspired by Java Programming Language. The first name of JavaScript was Mocha which was named by Marc Andreessen, Marc Andreessen is the founder of Netscape and in the same year Mocha was renamed LiveScript, and later in December 1995, it was renamed JavaScript which is still in trend.

What is JavaScript?

JavaScript is a client-side scripting language used with HTML (Hypertext Markup Language). JavaScript is an Interpreted / Oriented language called JS in programming language JavaScript code can be run on any normal web browser. To run the code of JavaScript, we have to enable JavaScript of Web Browser. But some web browsers already have JavaScript enabled.

Today almost all websites are using it as web technology, mind is that there is maximum scope in JavaScript in the coming time, so if you want to become a programmer, then you can be very beneficial to learn JavaScript.

JavaScript Hello World Program

In JavaScript, ‘document.write‘ is used to represent a string on a browser.

<script type="text/javascript">
	document.write("Hello World!");
</script>

How to comment JavaScript code?

• For single line comment in JavaScript we have to use // (double slashes)
• For multiple line comments we have to use / * – – * /

<script type="text/javascript">

//single line comment

/* document.write("Hello"); */

</script>

Advantages and Disadvantages of JavaScript

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Hire Dedicated JavaScript Developers -Hire JavaScript Developers

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