JavaScript syntax defines the set of rules for writing valid JavaScript code. Understanding syntax is the foundation of mastering JavaScript programming. Let's dive into the key aspects of JavaScript syntax.

1. JavaScript Character Set

JavaScript uses the Unicode character set, which includes:

• Letters (A-Z, a-z)

• Digits (0-9)

• Special characters like + - * / %

• Punctuation marks ; , .

• Whitespaces and escape sequences (like \n for a new line)

2. Values in JavaScript

Values are the fundamental units of JavaScript programming. They can be:

• Fixed values (also called literals) like 10, "Hello", or true

• Variable values stored in identifiers, e.g., let age = 25;

3. Literals in JavaScript

Literals are constant values directly written in code. Some common types include:

• Number literals: 42, 3.14

• String literals: 'JavaScript', "Hello"

• Boolean literals: true, false

• Null and Undefined literals: null, undefined

• Object literals: { name: "John", age: 30 }

• Array literals: [1, 2, 3, 4]

4. Variables in JavaScript

Variables store data in JavaScript. They are declared using:

• var (old way, not recommended for modern JS)

• let (preferred for variables that can change)

• const (used for values that should not change)

Example:

let name = "Alice";
const age = 25;
var city = "New York";

5. Operators in JavaScript

Operators perform operations on values and variables. Some common types:

• Arithmetic Operators: +, -, *, /, %

• Comparison Operators: ==, ===, !=, <, >

• Logical Operators: &&, ||, !

• Assignment Operators: =, +=, -=, *=

Example:

let sum = 5 + 3; // 8
let isEqual = (10 === "10"); // false

6. Expressions in JavaScript

Expressions produce values. Examples:

• Arithmetic expression: 10 + 20 (produces 30)

• Boolean expression: 5 > 3 (produces true)

• Function call expression: Math.max(5, 10)

7. Keywords in JavaScript

Keywords are reserved words with special meanings in JavaScript. Some common ones:

• if, else, return, function, class, break, switch, try, catch

Example:

if (age > 18) {
  console.log("Adult");
} else {
  console.log("Minor");
}

8. Comments in JavaScript

Comments improve code readability and are ignored by the JavaScript engine.

• Single-line comment: // This is a comment

• Multi-line comment:

  /*
     This is a multi-line comment
  */

9. Identifiers in JavaScript

Identifiers are names given to variables, functions, or objects.

Rules:

• Must start with a letter, _, or $

• Cannot be a JavaScript keyword

• Case-sensitive (myVar and myvar are different)

Example:

let firstName = "John";
let $price = 100;
let _count = 5;

10. Case Sensitivity in JavaScript

JavaScript is case-sensitive. This means age, Age, and AGE are different variables.

Example:

let user = "Alice";
let User = "Bob";
console.log(user); // Alice
console.log(User); // Bob

11. camelCase Naming Convention

JavaScript follows camelCase for naming variables and functions. This means the first word is lowercase, and subsequent words start with uppercase letters.

Example:

let firstName = "John";
function getUserName() {
  return "Alice";
}

Conclusion

Understanding JavaScript syntax is the first step in becoming a proficient JavaScript developer. Master these basics to write clean, efficient, and error-free code!