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What are variables in JavaScript?

Dear Friends to we will tell you what is variables in javascript and how implements in your projects. Now open the code editor and save it by selecting a new file and remember that while saving the file, you must write dot html because the browser has to explain it from html itself, without html we can not run any language That’s why it is very important for us to come to html for make a variables with javascript.

4 Ways to Declare a JavaScript Variables:

  • Using var
  • Using let
  • Using const
  • Using nothing

It’s interesting to note that there exist functional programming languages, like Scala or Erlang that forbid changing variable values.

In such languages, once the value is stored “in the box”, it’s there forever. If we need to store something else, the language forces us to create a new box (declare a new variable). We can’t reuse the old one.

Some variables

  1. 1. var, 2. const, 3. let.

In the above example, the msg variable is declared first and then assigned a string value in the next statement. The num variable is declared and initialized with a numeric value in the same statement. Finally, the hundred variable is declared and initialized with another variable’s value. JavaScript is a loosely typed language. It means it does not require a data type to be declared. You can assign any literal values to a variable, e.g., string, integer, float, boolean, etc.

Though it may seem a little odd at first sight, these languages are quite capable of serious development. More than that, there are areas like parallel computations where this limitation confers certain benefits. Studying such a language (even if you’re not planning to use it soon) is recommended to broaden the mind.

COLOR_ORANGE is much easier to remember than “#FF7F00”.
It is much easier to mistype “#FF7F00” than COLOR_ORANGE.
When reading the code, COLOR_ORANGE is much more meaningful than #FF7F00.
When should we use capitals for a constant and when should we name it normally? Let’s make that clear.

Being a “constant” just means that a variable’s value never changes. But there are constants that are known prior to execution (like a hexadecimal value for red) and there are constants that are calculated in run-time, during the execution, but do not change after their initial assignment.
Name things right
Talking about variables, there’s one more extremely important thing.

A variable name should have a clean, obvious meaning, describing the data that it stores.

Variable naming is one of the most important and complex skills in programming. A quick glance at variable names can reveal which code was written by a beginner versus an experienced developer.

In a real project, most of the time is spent modifying and extending an existing code base rather than writing something completely separate from scratch. When we return to some code after doing something else for a while, it’s much easier to find information that is well-labeled. Or, in other words, when the variables have good names.

Please spend time thinking about the right name for a variable before declaring it. Doing so will repay you handsomely.

Some good-to-follow rules are:

Use human-readable names like userName or shoppingCart.
Stay away from abbreviations or short names like a, b, c, unless you really know what you’re doing.
Make names maximally descriptive and concise. Examples of bad names are data and value. Such names say nothing. It’s only okay to use them if the context of the code makes it exceptionally obvious which data or value the variable is referencing.
Agree on terms within your team and in your own mind. If a site visitor is called a “user” then we should name related variables currentUser or newUser instead of currentVisitor or newManInTown.

What are Variables?

Variables are containers for storing data (storing data values).

In this example, xy, and z, are variables, declared with the var keyword:

In JavaScript, we can declare a variable in different ways by using different keywords. Each keyword holds some specific reason or feature in JavaScript. Basically we can declare variables in three different ways by using var, let and const keyword. Each keyword is used in some specific conditions.
var: This keyword is used to declare variable globally. If you used this keyword to declare variable then the variable can accessible globally and changeable also. It is good for a short length of codes, if the codes get huge then you will get confused.

const: This keyword is used to declare variable locally. If you use this keyword to declare a variable then the variable will only be accessible within that block similar to the variable defined by using let and difference between let and const is that the variables declared using const values can’t be reassigned. So we should assign the value while declaring the variable.

Naming Variables

Though you can name the variables as you like, it is a good programming practice to give descriptive and meaningful names to the variables. Moreover, variable names should start with a letter and they are case sensitive. Hence the variables student name and studentName are different because the letter n in a name is different (n and N).

HTML for make javascript code

Now open your vs code editor and go to the right top section and click on file and select new file then save filename.html after this press ctrl+1 then html syntax generate automatically on your editor. This feature inbuild only visual code editor so i suggested you download this editor and make projects easily because it is a best code editor software. And this design for stand fan project make a fast with visual studio code editor.


var x = 5;
var y = 6;
var z = x + y;


JavaScript Variable

  1. JavaScript variable  
  2. JavaScript Local variable  
  3. JavaScript Global variable  

JavaScript variable is simply a name of storage location. There are two types of variables in JavaScript : local variable and global variable.


There are some rules while declaring a JavaScript variable (also known as identifiers).

  1. Name must start with a letter (a to z or A to Z), underscore( _ ), or dollar( $ ) sign.
  2. After first letter we can use digits (0 to 9), for example value1.
  3. JavaScript variables are case sensitive, for example x and X are different variables.

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