Why prototypes are needed in Javascript - Quick Recap

Recall & Review

beginner

What is a prototype in JavaScript?

A prototype is an object that other objects inherit properties and methods from. It allows sharing features between objects without copying them.

beginner

Why do JavaScript objects use prototypes?

Prototypes let objects share methods and properties efficiently, saving memory and enabling easy updates to shared behavior.

intermediate

How do prototypes help with method sharing?

Instead of each object having its own copy of a method, the method lives on the prototype. Objects access it through the prototype chain.

intermediate

What happens if a property is not found on an object?

JavaScript looks up the prototype chain to find the property. If it exists on the prototype, it is used.

beginner

How do prototypes support code reuse?

By putting shared code on prototypes, many objects can reuse the same code without duplication, making programs smaller and faster.

What is the main purpose of prototypes in JavaScript?

A To create new variables

B To share properties and methods between objects

C To store data permanently

D To run code faster

Prototypes allow objects to share properties and methods, avoiding duplication.

If a property is missing on an object, where does JavaScript look next?

A In the prototype of the object

B In the global variables

C In the browser cache

D It throws an error immediately

JavaScript checks the object's prototype chain to find missing properties.

How do prototypes help save memory?

A By deleting unused variables

B By compressing code automatically

C By storing shared methods once on the prototype instead of in every object

D By running code in the background

Methods on prototypes are shared, so each object doesn't need its own copy.

Which of these is true about the prototype chain?

A It is used to find properties not directly on the object

B It stores all variables in the program

C It runs code faster by skipping steps

D It is a list of all functions in the program

The prototype chain helps locate properties and methods by checking prototypes.

What happens if a property is found on both the object and its prototype?

A An error occurs

B The prototype's property is used

C Both are used together

D The object's own property is used

The object's own property overrides the prototype's property.

Explain why prototypes are important in JavaScript and how they help objects share behavior.

Think about how many objects can use the same method without copying it.

Describe what happens when you try to access a property that an object does not have directly.

JavaScript looks beyond the object itself.