Javascript is a programming language that enables web developers to create interactive and dynamic features on webpages. It is an essential tool for any web developer, and Javatpoint’s Javascript tutorial provides a comprehensive overview of this powerful language. In this article, we’ll look at the syntax, structure, 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, working with cookies and local storage, security aspects of JavaScript, introducing AJAX (Asynchronous JavaScript and XML), building web applications using JavaScript, and advanced concepts of JavaScript.

What is Javascript?

Javascript is a scripting language based on the ECMAScript standard, which was originally developed in 1995 to give web browsers more interactive features. It is the programming language of the web, and provides web developers a way to add interactivity, animation, data manipulation, client-side form processing and more to websites. It is a programming language that runs in the client’s browser, and can be used to access and manipulate HTML elements on web pages with ease. Javascript code is executed by the computer’s processor, typically from within an HTML document or external .js file.

Javascript Syntax and Structure

Javascript syntax is quite straightforward, with some basic rules that must be followed in order for the code to execute properly. The basic syntax consists of functions, operators, scripts and keywords. Functions are pieces of code that execute specific tasks when called. Operators perform mathematical operations that result in a value. Scripts are groups of commands that can be executed as a group. Keywords are reserved words which have a specific purpose within the language.

Variables and Data Types in Javascript

Variables are locations in memory which are used to store data such as strings, numbers, Booleans, objects, and arrays. Variables are declared using the “var” keyword followed by a valid identifier or name for the variable. The data types which can be stored in variables include numbers, strings, Booleans (true or false values), objects and arrays. Numbers can be integers or floats, strings must be quoted using either double or single quotes, objects must be surrounded by curly braces, and arrays must be enclosed in square brackets.

Operators and Expressions in Javascript

Operators are used to perform operations on variables such as arithmetic calculations, comparisons, assignments and more. These include mathematical operators such as addition (+), subtraction (-), multiplication (*) and division (/). There are also comparison operators such as “==” which tests if two values are equal, “!=” which tests if two values are not equal, “>” which tests if one value is greater than another, and “<” which tests if one value is less than another. Finally, there are assignment operators such as “=” which assigns one value to another, “+=” which adds two values together and assigns the result to a variable.

Flow Control & Loops in Javascript

Flow control statements allow developers to control the flow of their code execution by executing certain pieces of code based on certain conditions or criteria. These statements include “if” statements which conditionally execute a block of code only if a condition is met, “switch” statements which execute a block of code based on a given value or condition from a set of options, “while” loops which repeatedly execute a block of code while a condition is true, “for” loops which repeat a block of code a certain number of times or until a set condition is met, “do” loops which repeat a block of code until a condition becomes false and “continue” and “break” statements which allow developers to break out of loops at certain points in their code.

Functions, Objects & Classes in Javascript

Functions are pieces of code that can be called and executed in order to perform a certain task or set of tasks. They allow developers to write code in an organized and reusable manner. Objects are collections of data typically represented as key-value pairs. These objects can contain properties (defined as key-value pairs) that can store values and methods (defined as functions) that can perform tasks when called upon. Classes are special objects which contain both properties and methods which can be shared across multiple objects in a given application.

Arrays & Strings in Javascript

Arrays are collections of data which can hold any combination of data types. Arrays are declared using square brackets ([]). Strings are sequences of characters that can be manipulated in various ways. Strings are declared using either single or double quotes (“” or ”).

Exception Handling & Debugging with Javascript

Exception handling is used to handle errors that may occur while executing a program. By using try/catch blocks within their code, developers can catch errors as they occur and allow their code to continue executing instead of crashing or throwing other errors. Debugging is used to identify errors within code so they can be fixed before they cause unforeseen problems.

Working with the DOM (Document Object Model) in Javascript

The Document Object Model (DOM) is a hierarchy of nodes used to represent HTML elements on web pages as objects. By manipulating node objects within the DOM tree using Javascript methods, developers can change content and stylings directly within HTML documents.

Working with Forms & Events in Javascript

Forms are used to capture user input on webpages. They can be manipulated using Javascript by setting values directly via DOM methods such as ‘querySelector’ or ‘getElementById’, or by using event listeners that capture user input events such as button clicks or text field changes. Event listeners allow developers to execute certain actions when certain events occur on their websites.

Working with Cookies & Local Storage in Javascript

Cookies are small pieces of data that can be sent from servers to client browsers to store information about users’ visits to websites. Local storage allows developers to store small amounts of data locally on client browsers for later retrieval or use. Both technologies allow for increased user experience as developers can store relevant information that can be used to improve their website or customize user interactions.

Security Aspects of JavaScript

When scripting websites with JavaScript it is important to consider security issues such as cross-site scripting (XSS) attacks and malicious code injection. Cross-site scripting is when malicious code is injected into web pages through user input. To avoid this type of attack it’s important to validate user input before it reaches the server and output any untrusted input as plain text instead of HTML code.

Introduction to AJAX (Asynchronous JavaScript and XML)

AJAX stands for Asynchronous JavaScript And XML. It is a technique used for updating parts of webpages without having to reload the entire page. The AJAX technique is made up of two main components; the XMLHttpRequest object for making server requests, and JavaScript for handling data sent from the server. AJAX allows for speedy interactions between client-side scripts and server-side scripts.

Building Web Applications Using JavaScript

JavaScript can be used to create full-blown web applications. Developers use various JavaScript libraries to create dynamic front end user interfaces which interact with back end services powered by various web technologies such as Node.js, MongoDB, PHP etc. JavaScript libraries such as ReactJS have become increasingly popular for building full stack web applications.

Advanced Concepts of JavaScript

As JavaScript has evolved over the years new advanced concepts have been introduced such as promises which are used for asynchronous programming, async/await function calls which allow developers write readable code while performing asynchronous operations such as making network requests or accessing databases seamlessly, custom elements used to create custom HTML elements, service workers used for caching resources for offline functionality, websockets used for creating realtime connections between clients and servers etc.