Identifiers in Javascript

An identifier is a name used to identify a variable, function, class, or other programming element.

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example:

//Variable Identifier

let firstNumber = 23;

let → keyword
firstNumber → Identifier
23 → value

// Function Identifier

#1
function greet(){
  console.log("Welcome to JavaScript!!.");
}

function → keyword
greet → Identifier

#2
function multiply(a,b){
  return a * b;
}

function → keyword
multiply → Identifier (function name)
a → Identifier (parameter)
b → Identifier (parameter)
return → keyword
* → arithmetic operator

// Class Identifier

class Person {};  //class → keyword and Persion → Identifier

// Object Identifier

const person = {
  name: "Ram",
  age: 23
};  // const → keyword and person → Identifier

Rules for Identifier’s Name:

• Can contain letters ( a-z, A-Z ), digits ( 0–9 ), underscore( _ ), dollar ( $ ).
• Must start with a letter, _, or $.
• Cannot start with a number.
• Cannot be a reserved keyword like ( for, const, let, if, ..).
• Javascript identifiers are case-sensitive.

// Valid Identifiers
let rules;
let rule1;
let _rule;
let $rule;
let firstRule;
let first_rule;

//Invalid Indentifiers
let 1rule;  // start with a number
let first-name;  // hyphen (-) not allowed
let first.name;  // dot (.) not allowed
let for;  // reserved keyword
let class;  // reserved keyword

Best Practices for Naming conventions:

• Variables and functions → camelCase

let firstName;
let lastName;
let totalAmount;
let myNameIsRam;

function addAll {};
function calculateTotal {};

• Constants → UPPER_SNAKE_CASE

const PI = 3.14159;
const MAX_USERS = 100;
const MIN_LENGTH = 8;

• Classes → PascalCase

class Person {};
class UserProfile {};