JavaScript Syntax:
JavaScript is a versatile scripting language that is primarily used for client-side web development. Here are some key elements of JavaScript syntax:
1. Statements and Comments:
Statements: JavaScript code is composed of statements, which are instructions that perform actions. Statements are typically terminated by a semicolon (`;`).
javascript
var x = 5; // Variable declaration and assignment statement
console.log(x); // Function call statement
Comments: Comments are used to add explanatory notes to the code. Single-line comments start with `//`, and multi-line comments are enclosed between `/*` and `*/`.
javascript
// This is a single-line comment
/*
This is a
multi-line comment
*/
 |
| JavaScript Syntax |
2. Variables and Data Types:
Variables:Variables are used to store and represent data. In JavaScript, you can use the `var`, `let`, or `const` keyword to declare variables.
javascript
var name = “John”; // Variable declaration with initial value
let age = 25; // Variable declaration with let
const pi = 3.14; // Variable declaration with const
Data Types: JavaScript has dynamic typing, meaning the data type of a variable is determined at runtime. Common data types include numbers, strings, booleans, objects, arrays, and functions.
javascript
var num = 42; // Number
var text = “Hello”; // String
var flag = true; // Boolean
var person = { // Object
firstName: “John”,
lastName: “Doe”
};
var numbers = [1, 2, 3]; // Array
3. Operators:
JavaScript supports various operators for performing operations on variables and values.
Arithmetic Operators:
javascript
var sum = 5 + 3;
var difference = 8 – 3;
var product = 4 * 2;
var quotient = 10 / 2;
Comparison Operators:
javascript
var isEqual = (a === b);
var isNotEqual = (a !== b);
var greaterThan = (x > y);
var lessThanEqual = (x <= y);
Logical Operators:
javascript
var andCondition = (a && b);
var orCondition = (x || y);
var notOperator = !isTrue;
4. Control Flow Statements:
Conditional Statements:
javascript
if (condition) {
// Code to execute if the condition is true
} else {
// Code to execute if the condition is false
}
Loops:
javascript
for (var i = 0; i < 5; i++) {
// Code to repeat in each iteration
}
while (condition) {
// Code to repeat as long as the condition is true
}
Switch Statement:
javascript
switch (expression) {
case value1:
// Code to execute if expression equals value1
break;
case value2:
// Code to execute if expression equals value2
break;
default:
// Code to execute if expression doesn’t match any case
}
5. Functions:
Functions are blocks of reusable code that can be defined and called.
javascript
function greet(name) {
return “Hello, ” + name + “!”;
}
var greeting = greet(“John”);
console.log(greeting);
This is a basic overview of JavaScript syntax. JavaScript is a versatile language with many features, and its syntax allows developers to create dynamic and interactive web applications.