Javatpoint JavaScript Tutorials in details for Freshers with

JavaScript Javatpoint Tutorials for Beginners

What is JavaScript Explain In Details?

In the present day, one of the most utilized programming languages is JavaScript, a language critical for web development, backend services, and even mobile apps. The focus of this tutorial is to discuss core JavaScript concepts, the modern-day problems developers face, and the solutions.

Javascript is a computer programming language that enables the creation of interactive and dynamic elements for webpages by web developers. It is the building block for every web developer, while Javatpoint’s Javascript tutorial covers this important language in its entirety. This article seeks to discuss the syntax and structure of data types, operators and expressions, flow control, and loops. functions, classes, and objects; arrays and strings; exception handling and debugging; working with the DOM (Document Object Model); working with forms and events alive.Work with cookies and local storage; security aspects of JavaScript; introduction to AJAX (Asynchronous JavaScript and XML); development of web applications using JavaScript and advanced concepts in JavaScript.

JavaScript and Its History

In 1995, a certain Brendan Eich created JavaScript while working for Netscape. Mocha was its original name, afterward renamed LiveScript, and later JavaScript. The process of standardizing the language first dubbed ECMAScript (in 1997) continues to this day with improvements in the likes of ES5 (2009), ES6 (2015), and beyond.

Evolution of JavaScript

1995: JavaScript was developed and implemented in Netscape Navigator.

1997: ECMAScript 1 (ES1) was standardized.

2009: ECMAScript 5 (ES5) introduced strict mode and array methods.

2015: ECMAScript 6 (ES6) brought major changes like let/const, arrow functions, and modules.

2017-Present: Yearly ECMAScript updates introduce new features like async/await, optional chaining, and private class fields.

Data Types and Variables in JavaScript javatpoint

The memory locations occupied by variables are used to store data in the form of strings, numbers, Booleans, objects, and arrays. A variable is declared by using the keyword ‘var’ and giving it a valid identifier or name. Variables may hold data in the form of numbers, strings, Booleans (true or false values), arrays, and objects. Numbers may be either integer or floating-point. Strings must be surrounded by either double or single quotation marks, an object by curly braces, and an array by square brackets.

JavaScript provides three ways to declare variables:

var is a kind of function-scoped facilities and can be redone/generated on program level ( though disadvantages when used in current modern javascript).

let is a block scope feature and allows reassignment.

const-also a block scope and cannot be reassigned.

Example:

var globalVar = "I am global";
let name = "John";
const age = 30;

Data Types in javascript explain In details

JavaScript has several data types, categorized into primitive and non-primitive

Primitive Data Types

1. String – Represents text

let text = "Hello, world!";

Number – Represents both integers and floating-point numbers.

let score = 100;
let temperature = 36.5;

Boolean – Represents true or false values.

let isActive = true;

Undefined – A variable that has been declared but not assigned a value.

let notDefined;
console.log(notDefined); // undefined

Null – Represents an empty or unknown value.

let emptyValue = null;

Symbol – Used for creating unique values.

let uniqueID = Symbol("id");

Non-Primitive Data Types In JavaScript Explain In details

1. Object – A collection of key-value pairs.let user = { name: "Alice", age: 25 };

let user = { name: "Alice", age: 25 };

1. Array – An ordered collection of values.let colors = ["red", "green", "blue"];

let colors = ["red", "green", "blue"];

1. Function – A reusable block of code.

function greet(name) {
    return `Hello, ${name}!`;
}
console.log(greet("Alice"));

What are Operators and Expressions in JavaScript

Operators are used to operate on variables for purposes like arithmetic, comparisons, or assignments. Arithmetic operators include + for addition, – for subtraction, * for multiplication, and / for division. Comparison operators include ==, which tests for equality between two values; !=, which tests for inequality of two values; >, which checks if one value is greater than the other; and <, which checks if one value is less than another. Finally, assignment operators assign a new value to an existing variable (=), add two values and assign the result to a variable (+=), and so on.

Javascript Syntax and its Structure

The JavaScript syntax is fairly easy and simple as there are rules to follow. In order to allow proper execution of the code, certain basic syntax should be learned, including functions, operators, scripts and keywords. A function is a piece of code that has the ability to perform a specific function on being called. It performs certain mathematical operations which ultimately lead to a value. A script is a compilation of statements or commands that can as well be executed as a whole. Keywords are reserved words which serve a purpose in the language.

Objects & Classes ,Functions in Modern Javascript

A function is, basically, a set of codes that can be executed when called upon to perform some specific task or tasks. Functions allow developers to organize and reuse code. An object is a collection of data normally represented as key-value pairs. These objects can have properties (usually defined as key-value pairs), which hold values for some particular purpose, and methods (functions) that do certain jobs when called upon. Classes are special objects, which basically contain properties and methods that can be shared across many objects within a given application.

JavaScript arrays and strings

Arrays hold data collections of different types. They are declared by square brackets. Strings are just sequences of characters used for various functions. Strings are declared using either single or double quotes (“” or ”).

Exception Handling and Debugging with Javascript

An exception handling mechanism is used to handle errors that can occur while executing a program. Developers will program error handling statements in the form of a try/catch block. This type of program exception handling requires that the code continue running without crashing into further exceptions even when an error occurs. A debugging technique is used to identify errors within the code, so they can be fixed, and further prevent unforeseen problems.

JavaScript DOM Programming

The Document Object Model is defined as a hierarchy of nodes representing HTML elements of web pages in such a way that these elements appear as objects. Hence, here by manipulating the node object within the DOM tree using Javascript methods, one can change the content and styling within the HTML documents.

Working Form & Event in Javascript

Forms are used to capture user input on the website pages. This user input can also be manipulated using Javascript by simply setting the values directly through the DOM methods ‘querySelector’ or ‘getElementById,’ or calling even listeners that catch user input events and registers them accordingly, such as on a button click or even a text field change. With event listeners, developers can trigger specific actions upon certain events within their websites.

Working with Cookies and Local Storage in Javascript

Cookies are small pieces of data that can be transmitted from server to the client’s browser to store information about the visits that a user makes to a specific site. Local storage can be used to store small amounts of data on clients’ browsers locally from where they can retrieve or reuse that data later. Both features enhance usability through the provision of storage for relevant information, which can be used to improve the website or customize user interactions.

Security Aspects of JavaScript

As any scripting for websites with JavaScript, it is important to look into the security issues that are caused by cross-site scripting or the injection of malicious code. Cross-site scripting refers to the injection of malicious scripts into web pages through user input. Validation of input before it ever reaches the server and outputting any unwelcome input as plain text rather than HTML would be sound stipulations against such attacks.

What exactly is AJAX?

AJAX is simply Asynchronized JavaScript and XML. Using this technology makes page refreshes unnecessary but enables updating certain portions of the pages at a time. The primary components of AJAX are: big XMLHttpRequest object to request the server, and JavaScript for containing data sent to the server. AJAX allows quick interactions between client-side scripts and server-side scripts.