The ultimate guide to coding interviews: Learn and practice JavaScript design patterns tested by FAANG engineers. Get interview-ready in just a few hours with battle-tested solutions.

If you're an experienced developer, chances are your interviewer won't ask you about language syntax. Instead, they'll focus on things that test your understanding of software architecture, and how capable you are at finding optimized solutions to given problems. 

That’s where a strong understanding of design patterns comes in handy. It's often useful to be able to draw on established patterns instead of reinventing the wheel.

In this course, you will learn how to effectively deploy design patterns to answer interview questions. The course is divided into four sections: Creational Patterns, Structural Patterns, Behavioral Patterns, and Architectural Patterns. Each section has its own set of design patterns which you’ll learn to use through various challenges. 

Every challenge contains a detailed solution explanation. By the end of this course (and with some practice), you will be able to confidently use design patterns to tackle advanced coding interview questions in JavaScript.

JavaScript Design Patterns for Coding Interviews

## What is the flyweight pattern?

It is a structural pattern that focuses on how related objects share data. It helps prevent repetitive code and increases efficiency when it comes to data sharing as well as conserving memory.

This pattern takes the common data structures/objects that are used by a lot of objects and stores them in an external object (**flyweight**) for sharing. You could say that it is used for caching purposes. So, the same data does not need to have separate copies for each object, instead, it is shared amongst all. 

A *flyweight* is an independent object that can be used in multiple contexts simultaneously. It cannot be distinguished from the instances of objects that are not sharable. A flyweight object can consist of two states:

* **intrinsic:** this state is stored in the flyweight. It contains the information required by the internal methods of objects. It is independent of the context of the flyweight and is sharable with other objects.

* **extrinsic:** this state depends on the context of the flyweight and it cannot be shared. Normally, the client objects pass the extrinsic state to the flyweight object when needed.

# What is the flyweight pattern?

It is a structural pattern that focuses on how related objects share data. It helps prevent repetitive code and increases efficiency when it comes to data sharing as well as conserving memory.

This pattern takes the common data structures/objects that are used by a lot of objects and stores them in an external object (**flyweight**) for sharing. You could say that it is used for caching purposes. So, the same data does not need to have separate copies for each object, instead, it is shared amongst all. 

A *flyweight* is an independent object that can be used in multiple contexts simultaneously. It cannot be distinguished from the instances of objects that are not sharable. A flyweight object can consist of two states:

* **intrinsic:** this state is stored in the flyweight. It contains the information required by the internal methods of objects. It is independent of the context of the flyweight and is sharable with other objects.

* **extrinsic:** this state depends on the context of the flyweight and it cannot be shared. Normally, the client objects pass the extrinsic state to the flyweight object when needed.

In this lesson, we will discuss the flyweight pattern in detail with the aid of a coding example.


Before We Begin

Introduction To Design Patterns

Creational Patterns

Structural Patterns

Behavioral Patterns

Architectural Patterns

Conclusion

Flyweight Pattern

What is the flyweight pattern?