Python arsenal development-front-end chapter - Introduction to JavaScript (33)

Introduction to JavaScript in the front-end chapter (33)

Introduction to JavaScript

JavaScript is a scripting language used to provide interactivity and dynamics to websites and applications. It is a high-level programming language that can be used to create a variety of features, including web form validation, dynamic effects, graphical interactions, application development, and more. Since JavaScript is an interpreted language, it does not require compilation and can run directly in a web page or application. JavaScript is often used together with HTML and CSS to create dynamic web applications. It plays a vital role in modern web development as it enables developers to create interactive web pages and applications that make the web experience richer and more vivid.

JavaScript is a lightweight scripting language mainly used for interaction and dynamic effects on Web pages. It can be embedded in HTML or referenced into HTML as a separate JavaScript file. JavaScript has the advantages of being dynamic, interactive, and cross-platform, and can perform complex interactions and logical processing of front-end pages.

Main features of JavaScript:

1. Lightweight programming language: JavaScript itself does not require particularly powerful computing power and can run on any browser, making it one of the most common scripting languages ​​in web development.

2. Interpreted Programming Language: JavaScript is an interpreted scripting language. It does not require a compiler for compilation and is directly interpreted and executed by the interpreter at runtime. This means developers can quickly test and modify code.

3. Works with HTML and CSS: JavaScript can modify HTML and CSS codes to achieve dynamic page effects.

4. Cross-platform: JavaScript is executed inside the browser, not on the operating system. Therefore, it is not restricted to a specific operating system.

5. Object-oriented programming language: JavaScript is an object-oriented programming language. Developers can use object-oriented programming features such as classes, objects, inheritance, and polymorphism to develop Web applications.

The main application areas of JavaScript include web page special effects, form validation, data interaction, AJAX technology, dynamic pages, etc. It is an integral part of web development.

What JavaScript can do

JavaScript is a scripting language that is primarily used for writing web applications, but can also be used for desktop applications, game development, and mobile applications. Here are some of the things JavaScript can do:

1. Dynamically update web page content and interact with users;

2. Create animations, images and visual effects;

3. Browser-side validation of form input data;

4. Interact with backend servers to send and receive data;

5. Send AJAX requests to update content without refreshing the page;

6. Develop back-end applications based on Node.js;

7. Develop desktop applications, games, and mobile applications;

8. Develop browser plug-ins and extensions;

9. Develop artificial intelligence and machine learning applications;

10. Develop blockchain and cryptocurrency applications and more.

The relationship between JavaScript and penetration

JavaScript can be used for front-end interaction in websites, but it can also be used to implement some security and attack techniques. During penetration testing, attackers can use JavaScript vulnerabilities to break through the website's security protection, such as XSS (cross-site scripting attacks) and CSRF (cross-site request forgery) attacks, because JavaScript can set and read cookies, perform HTTP requests and Modifying page content and other operations may cause the website to be tampered with or data stolen. In turn, security professionals can use JavaScript to detect and exploit vulnerabilities and implement some targeted security measures and fixes. Therefore, JavaScript has certain importance and application value in the field of penetration testing and security.

JavaScript plays an important role in penetration testing. Here are some of the relationships between JavaScript and penetration:

1. Attackers can use JavaScript to develop and execute attack scripts to manipulate target systems, steal data, or exploit vulnerabilities.
2. JavaScript can be used to exploit vulnerabilities in web browsers to access protected data or take control of a compromised machine.
3. JavaScript can be used to scan target sites for vulnerabilities and weaknesses that can be exploited to compromise the system.
4. Penetration testers can use JavaScript to test the security of a target site and verify possible vulnerabilities.
5. Penetration testers can use JavaScript to develop various tools and scripts for automated penetration testing and vulnerability scanning.
6. JavaScript files leak background management sensitive paths and api (upload files through api structure getshell)
7. Penetration testers can find that JavaScript files in the page leak http-only protected cookies. Front-end developers usually write http-only protected cookies in the page.
8. Penetration testers can find that jJavaScript files and ajax requests within the page leak sensitive user information

In general, JavaScript is a very important tool in penetration testing, and attackers will also use it to achieve penetration attacks on target systems. Therefore, attention needs to be paid to protecting the JavaScript code of the website to prevent it from being exploited by attackers. At the same time, penetration testers also need to have an in-depth understanding of JavaScript language-related technologies in order to better conduct penetration testing and security assessments.

The composition of JavaScript

JavaScript consists of three main parts:

1. Core JavaScript: This includes the basic syntax, data types, control structures, and functions of the language itself. It provides the basic building blocks needed to write dynamic web applications.
2. DOM (Document Object Model): It is a programming interface for Web pages, used to access and manipulate the content and structure of documents. DOM can use JavaScript to operate elements on the page, such as changing text and styles, adding and deleting elements, etc.
3. BOM (Browser ObjectModel): It provides methods to access and manipulate browser windows and frames. BOM includes some objects, such as window, location, history, screen, etc., which can be used to control browser behavior, such as opening new windows, redirecting to other pages, etc.