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One of the most influential works on JS design patterns was produced by Gamma et al., entitled Design Patterns: Elements of Reusable Object-Oriented Software (1994). The text describes the twenty-three set design patterns that are still used in JS pattern work today.
For example, consider a team building hybrid cloud infrastructure for a client. These systems require a lot of connectivity power, so one of their common issues might be problems with communication between software. With this level of complexity, a development team may not have time to find a new solution each time they encounter this problem.
This is where design patterns come in. Once the issue has been solved once, that solution can then be applied to other instances of the same problem.
Terminology – Design Patterns
- Class: a function for creating objects and dictating their actions.
- Object: a single item with a type and set properties.
- Interface: the combination of data and properties within an object.
- Method: the relationship between an object and a commanding message, e.g. is the object and are the messages.
- Instantiation: creating a new action or context based on a specific model.
- Structure: diagrams of the objects and classes that show parts of the system and how it functions.
It’s important to express important information relating to your system in a standard form that every programmer in your team can understand clearly.
- Practice: get to know object-oriented programming in more detail.
- Maintenance: design patterns can help you to maintain your code database and avoid it becoming overcrowded – implementing the “Don’t Repeat Yourself!” principle.
- Ease: one of the best things about design patterns is that you can avoid doing unnecessary work that could make your code more complicated in the long run.
Most app developers will come to know what issues they face on a regular basis. Design patterns are a way of managing these and talking about them in a common way.
Take designing data visualization software as an example. Developers may find that common issues include problems with communication between data inputs and disordered data processing steps. These teams will come to know the codes for these solutions and apply them to similar issues in the future.
Another key idea here that we’ve touched on already is maintainability. As most industries undergo some form of digital transformation, programmers are having to keep up with changing customer demands. Being able to maintain your code sets without unnecessary complexity is a must in today’s business environment.
Three Core Pattern Types You Need to Know
There are three core types of JS design pattern types. Each one has a specific function in the development of new applications and works to solve a different issue. There are 23 pattern types that fall under these three core categories.
1. Creational Pattern
Once you’ve identified the spots that often cause this problem, you can extract code from previous repairs and use this as a template for solving future issues.
There are four major patterns that come under this umbrella:
- Constructor: a simple pattern used to help with creating constructors (a code feature that activates new objects once their memory has been allocated). Alternatively, you may use a builder pattern.
- Singleton: sometimes known as a strict pattern, this limits the instantiation of a creator template (class) to one instance. This is used when one object is used to coordinate multiple actions across a system.
- Prototype: a pattern used to instantiate new objects based on existing ones, supporting cloning of coded components.
- Factory: related to a constructor pattern, a factory pattern is used for creating objects using a defined interface. A subtype of this is an adaptor factory.
Creator patterns are a great place to start your learning journey for JS design patterns.
2. Structural Pattern
Structural design patterns are patterns that are used for object composition. They can be used to assemble objects into classes and classes into a larger system. They can also be used to keep the system working normally when one part is changed.
There are seven types of structural design patterns:
- Adapter: sometimes known as a wrapper pattern. It is one that allows one existing interface to be used as a different interface.
- Composite: a pattern that causes multiple objects to be treated like a single entity in part/whole diagrams.
- Bridge: these patterns separate an object’s abstraction (removal or halting of properties) from its implementation (its trigger or initiating command).
- Facade: a pattern that acts as a surface-facing cover for more complex systems or code underneath.
- Decorator: these patterns allow features or actions to be added to single objects.
- Proxy: a pattern that acts as an interface to another object or system.
- Flyweight: these patterns reduce memory usage in an object by sharing its data with other components of similar properties.
Structural patterns can be used in the development and manufacturing of software. The line between development vs manufacturing can sometimes be difficult to see in software engineering, so you may find that both teams need similar skills. Understanding structural patterns is vital to a smooth development process for even simple software.
3. Behavioral Pattern
Behavioral design patterns are patterns that control the designation of responsibility and functions to objects within a system. They can help to improve the level of communication between system parts.
There are ten types of behavioral patterns:
- Chain of responsibility: this pattern assigns chief responsibility to one object in a system and processing responsibilities that the subsequent objects.
- Command: a pattern that orders an object to contain all relevant information to an action or command, including its trigger.
- Mediator: this pattern defines how a set of objects interact, contained within a single object.
- Iterator: this pattern can access a container object and view the information within it.
- Observer: a pattern that causes an object (the subject) to track its dependent components (observers) and relay messages when the system changes in any way.
- Memento: these patterns restore objects or systems to their previous state, for example, in cases of malfunction or system error.
- State: a pattern that allows an object to alter its behaviors when its state is changed.
- Strategy: these patterns allow run-time instructions to determine which algorithms a system uses. They’re also known as policy patterns.
- Template method: this pattern outlines an operation’s steps in terms of high-level steps in a superclass.
- Visitor: these patterns separate a given object structure from its algorithm, allowing new steps to be inserted into a system with minimal interruption.
Their purpose is to avoid spending valuable time solving common coding problems and making your code as simple as possible. By understanding what JS design patterns are and their essential types, you’ve taken a great first step in learning how and when to use them.
About the Writer
Grace Lau – Director of Growth Content, Dialpad. Grace is the Director of Growth Content at Dialpad, an AI-powered cloud communication and business phone app platform for better and easier team collaboration. She has over 10 years of experience in content writing and strategy. Currently, she is responsible for leading branded and editorial content strategies, partnering with SEO and Ops teams to build and nurture content. She has written for sites such as Test Project and Crocoblock. Here is her LinkedIn.