Learn about JavaScript's insecure code patterns that lead to code injection vulnerabilities in Node.js applications. This book provides a comprehensive guide to code security in server-side JavaScript applications and how to mitigate code injection vulnerabilities by analyzing real-world security vulnerabilities reported as CVE to popular open-source npm packages. This book begins by laying the foundations of application security and continues to unfold the theory and practice behind code injection vulnerabilities. It then takes a hands-on approach to vulnerable code, demonstrating how insecure JavaScript and Node.js APIs lead to code injection security risks. Following vulnerable code reviews with applied security vulnerabilities will teach you how to recognize and avoid insecure code patterns in your Node.js applications. The more you spend time reading code, the easier it becomes to grasp its intricacies and gain deeper contextual understanding. This book's primary objective is to facilitate that learning process by examining vulnerable code, allowing us to learn from its flaws. This activity cultivates patterns within our cognitive processes, enabling our brains to identify and recognize security red flags and code insecurity swiftly. These acquired patterns become invaluable assets in daily programming and code review routines, enhancing your ability to proactively detect and mitigate security vulnerabilities.