JavaScript syntax is the set of rules that define how we write and structure JavaScript code. It includes elements like statements, variables, functions, operators, and control flow (such as loops and conditions). Following these rules ensures that the code runs correctly and efficiently.

Syntax

console.log("Basic Print method in JavaScript");

JavaScript syntax refers to the set of rules that determines how JavaScript programs are constructed:

// Variable declaration
let c, d, e;
 
// Assign value to the variable
c = 5; 
 
// Compute value of variables
d = c;
e = c / d;

JavaScript Values

There are two types of values defined in JavaScript Syntax:

• Fixed Values: These are known as the literals.
• Variable Values: These are called variables.

These are the features of JavaScript which have some predefined syntax:

Table of Content

• JavaScript Literals
• JavaScript Variables
• JavaScript Operators
• JavaScript Expressions
• JavaScript Keywords
• JavaScript Comments
• JavaScript Data Types
• JavaScript Functions
• JavaScript Identifiers

JavaScript Literals

Syntax Rules for the JavaScript fixed values are:

• JavaScript Numbers can be written with or without decimals.
• JavaScript Strings are text that can be written in single or double quotes.

let num1 = 50;
let num2 = 50.05;
 
let str1 = "Coding";
let str2 = 'Coding75';
 
console.log(num1);
console.log(num2);
console.log(str1);
console.log(str2);

Output:

50
50.05
Coding
Coding75

JavaScript Variables

A JavaScript variable is the simple name of the storage location where data is stored. There are two types of variables in JavaScript:

• Local Variables: Declared inside a block or function.
• Global Variables: Declared outside a function or with a window object.

Example:

// Declare a variable and initialize it
let Name = "Apple";
 
// Function definition
function MyFunction() {
    let num = 45;
    console.log(Name);
    console.log(num);
}
 
// Function call
MyFunction();

Output:

Apple
45

JavaScript Operators

JavaScript operators are symbols used to compute values. Arithmetic operators (+, -, *, /) are used to compute values, while assignment operators (=, +=, %=) assign values to variables.

Example:

// Variable Declarations
let x, y, sum;
 
// Assign values to variables
x = 3;
y = 23;
 
// Add two numbers
sum = x + y;
console.log(sum);

Output:

26

JavaScript Expressions

A JavaScript Expression is a combination of values, operators, and variables used to compute values.

Example:

let x, y, num, sum;
x = 20;
y = 30;
num = x / 2;
sum = x + y;
console.log(num + "\n" + sum);

Output:

10
50

JavaScript Keywords

The keywords are reserved words that have special meanings in JavaScript.

let a, b;
function GFG() {};

JavaScript Comments

Comments are ignored by the JavaScript compiler, improving code readability.

Example:

let x, y, sum;
x = 20;
y = 30;
/* Expression to add two numbers */
sum = x + y;
console.log(sum);

Output:

50

JavaScript Data Types

JavaScript provides different data types:

let txt = "GeeksforGeeks";
let a = 5, b = 5;
console.log(a === b); // true
let places = ["Coding", "Computer", "Hello"];
let Student = {
    firstName: "Johnny",
    lastName: "Diaz",
    age: 35,
    mark: "blueEYE"
};

JavaScript Functions

JavaScript functions are reusable blocks of code.

function func() {
    let num = 45;
    console.log(num);
}
func();

Output:

45

JavaScript Identifiers

JavaScript Identifiers are names used for variables, functions, and keywords. They must begin with:

• A letter (A-Z or a-z)
• A dollar sign ($)
• An underscore (_)

Example:

let firstName = "Coding";
let firstname = 100;
console.log(firstName);
console.log(firstname);

Output:

Coding
100

JavaScript Camel Case

JavaScript prefers camelCase for naming identifiers.

let firstName;
let lastName;