Five Design Patterns to know in Node.js

The page introduces design patterns as tested solutions for recurring development problems and says Node.js lets developers choose the patterns they need. It then walks through five patterns and shows their use with small class examples.

Singleton is presented as a way to keep a single shared instance, useful for one connection to Redis or similar services. Factory abstracts object creation, Observer manages a list of subscribers and notifies them on state changes, Decorator extends existing functionality without changing the original class, and Dependency Injection passes services in from outside so they can be reused and tested more easily.

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• Define design patterns as tested solutions for recurring problems in software development and as a way to promote best practices and structured design.
• Says Node.js gives freedom to choose only the patterns needed for a task instead of forcing one approach.
• Presents Singleton as a pattern with one instance and global access, illustrated with a Redis connection shared through module caching.
• Describes Factory as a way to create objects without naming the concrete class directly, improving readability and reuse.
• Explains Observer as a setup where one entity keeps a list of observers and notifies them when state changes, which helps with event handling and asynchronous workflows.
• Shows Decorator as a way to add functionality to an existing class without changing its original instance or core behavior.
• Presents Dependency Injection as receiving services from outside the class or module, which makes testing and maintenance easier.
• Notes that these patterns are used in frameworks such as Nest.js and Vue.js.