Variables in JavaScript

Zia

1 Follower

Aug 13, 2024

0 sec read

208

A variable refers to a symbolic name that holds a value, which keeps changing. For example, the age of a student and the salary of an employee can be treated as variables. A real-life example of variables includes the variables used in algebraic expressions that store values.

In JavaScript, a variable is a unique location in the computer's memory that stores a value and has a unique name. The name of the variable is used to access and read the value stored in it. A variable can store different types of data such as a character, a number, or a string. Therefore, a variable acts as a container for saving and changing values during the execution of the script.

1. Declaring Variables

Declaring a variable refers to creating a variable by specifying the variable name. For example, you can create a variable named studName to store the name of a student. Here, the variable name studName is referred to as an identifier. In JavaScript, the var keyword is used to create a variable by allocating memory to it. A keyword is a reserved word that holds a special meaning in JavaScript.

You can initialize the variable at the time of creating the variable or later. Initialization refers to the task of assigning a value to a variable. Once the variable is initialized, you can change the value of a variable as required.

Variables allow keeping track of data during the execution of the script. While referring to a variable, you are referring to the value of that variable. In JavaScript, you can declare and initialize multiple variables in a single statement.

The following syntax demonstrates how to declare variables in JavaScript:

Syntax:

var <variableName>;

where,

var: ls the keyword in JavaScript.
variableName: This is a valid variable name.

The following syntax demonstrates how to initialize variables in JavaScript:

Syntax:

<variableName> = <value>;

where,

=: Is the assignment operator used to assign value.
Value: This is the data to be stored in the variable.

The following syntax demonstrates how to declare and initialize multiple variables in a single statement, which are separated by commas.

Syntax:

var <variableName1> = <value1>, <variableName2> = <value2>;

Two variables namely, studID and studName and assign values to them.

var studID;

var studName;

studID = 50;

studName = "David Fernando";

This code assigns values to studID and studName variables by using the assignment operator (=). The value named David Fernando is specified within double quotes.

How to declare and initialize multiple variables in a single statement in JavaScript.

var studName =David, studAge = 15:

2. Variable Naming Rules

You cannot refer to a variable until it is created in JavaScript. JavaScript is a case-sensitive language. This means that if you specify X and x as variables, they are treated as two different variables. Similarly, in JavaScript, there are certain rules, which must be followed while specifying variable names.

These rules for a variable name are as follows: