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For example:
var age = 16;
var name = "A"
We can declare multiple variables in the same line in the following way:
var v1 = 1, v2 = 'Delhi', v3;
Variable Naming Conventions
In JavaScript, variable naming conventions are important to make code more readable and maintainable.
Some rules and best practices for naming variables in JavaScript are as follows:
Ð ÐCamel Case Notation: JavaScript variables are typically written in camelCase. The first word starts with a lowercase
letter, and each subsequent word starts with an uppercase letter.
Example:
let firstName = "John";
let totalAmount = 100;
Ð ÐCase Sensitivity: JavaScript variable names are case-sensitive. This means firstName, Firstname, and firstname are
all different variables.
Ð ÐDescriptive Names: Use meaningful names that describe the value the variable holds or the purpose it serves.
let userAge = 25; // good
let x = 25; // not descriptive
Ð ÐAllowed Characters: Variable names can include Letters (a-z, A-Z), Digits (0-9), dollar sign ($), underscore (_).
However, variable names cannot start with a digit.
Example:
let myVar1 = 10; // valid
let 1stVar = 20; // invalid, starts with a number
Ð ÐNo Reserved Keywords: Variable names cannot be JavaScript reserved words. In JavaScript, reserved words (or
keywords) are words that have a specific meaning in the language syntax. These words cannot be used as identifiers,
such as variable names, function names, or class names, because they are already reserved for specific purposes
by the language.
abstract char double for int private synchronized typeof
arguments const else function interface protected this void
boolean continue eval goto long public throw volatile
break debugger false if native return throws while
byte default final implements new short transient var
case delete finally in null static true with
catch do float instanceof package switch try yield
Ð ÐConstants in Upper Case: Variables that hold constant values are often written in UPPERCASE letters, with
underscores to separate words.
Example:
const MAX_SPEED = 120;
const PI = 3.14159;
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