Modern JavaScript from the Beginning - Second Edition - Sealing and Freezing Objects

This video tutorial explains the concepts of sealing and freezing objects in JavaScript. Sealing an object prevents new properties from being added or existing ones from being removed, but allows modification of existing properties. Freezing an object locks down all properties, preventing any changes. The video demonstrates these concepts with examples, using methods like Object.seal and Object.freeze, and shows how to check if an object is sealed or frozen using isSealed and isFrozen methods. The tutorial aims to provide a comprehensive understanding of object property management.

What is the main difference between sealing and freezing an object?

• Sealing allows adding properties, freezing does not.

• Sealing allows modifying properties, freezing does not.

• Freezing allows removing properties, sealing does not.

• Freezing allows adding properties, sealing does not.

What happens when you try to add a new property to a sealed object?

• The property is added but not enumerable.

• The property is added successfully.

• The property is added but not writable.

• The property is not added.

In the rectangle example, what property was successfully modified after sealing?

• Height

• Color

• Name

• Width

What is the effect of freezing an object on its properties?

• Properties can be added but not removed.

• Properties can be modified but not added.

• Properties can be removed but not modified.

• Properties cannot be added, removed, or modified.

In the circle example, what was the result of trying to change the name property after freezing?

• The name was changed successfully.

• The name was removed.

• The name remained unchanged.

• The name was set to null.

What does the isSealed method check for in an object?

• If the object has enumerable properties.

• If the object is frozen.

• If the object is sealed.

• If the object has writable properties.

What is true about an object that is frozen?

• It can have properties modified.

• It is also sealed.

• It can have properties removed.

• It can have properties added.