JavaScript design patterns are established solutions for common software design issues, enhancing code reuse and maintainability. These patterns, rooted in object-oriented principles, were formalized in 1994 by the "Gang of Four" and have since evolved, including Creational, Structural, and Behavioral categories, each with specific roles in object creation, composition, and interaction. The blog explains popular JavaScript design patterns like Singleton, Factory, Module, and Observer, offering a structured approach to coding. It also touches on Anti-Patterns, which are poor coding practices, and suggests using the LambdaTest platform for cross-browser testing to ensure pattern implementation consistency. The blog concludes by recommending resources like Addy Osmani’s "Learn JavaScript Design Patterns" for deeper understanding.