Singleton Pattern

The video tutorial introduces the Singleton pattern, a design pattern that ensures only one instance of an object is created. It explains the pattern's relation to the module pattern and its use cases, such as managing a single user session. Despite its utility, the Singleton pattern is often criticized for providing a global point of access, which can hinder encapsulation and debugging. The tutorial includes a JavaScript implementation example, demonstrating how to create and test a Singleton instance. The video concludes with a brief mention of the upcoming topic, the factory pattern.

What is a key characteristic of the Singleton pattern?

• It provides a global point of access to a single instance.

• It is only applicable in JavaScript.

• It is used to create multiple objects.

• It allows multiple instances of an object.

Why might some developers be hesitant to use the Singleton pattern?

• It is not supported in most programming languages.

• It can be difficult to debug and breaks encapsulation.

• It is too complex to implement.

• It encourages encapsulation.

In the JavaScript example, what is the purpose of the 'createInstance' function?

• To log the instance to the console.

• To create multiple instances of an object.

• To initialize a new object only if one doesn't already exist.

• To delete an existing instance.

How does the example ensure that only one instance of the object is created?

• By using a global variable to store multiple instances.

• By using a loop to check for existing instances.

• By using a conditional statement to create an instance only if it doesn't exist.

• By creating a new instance every time the function is called.

What does the console log output when comparing two instances created from the Singleton?

• Undefined, because the instances are not initialized.

• An error, because comparison is not allowed.

• False, because they are different instances.

• True, because they are the same instance.