How do you get the number of properties in an obj...
A). Object.keys(book).length
B). book.countProperties()
C). book.totalProperties()
D). book.length()
How do you define a method 'sayHello' in an obj...
A). person.sayHello = function() {};
B). person.sayHello: function() {};
C). person.sayHello = () {};
D). person.sayHello = function {};
How do you add a new property 'age' with value 25...
A). person.age = 25;
B). person['age'] = 25;
C). person.add('age', 25);
D). person.push('age', 25);
How do you iterate over all properties of an obj...
A). for (var prop in person)
B). forEach(prop in person)
C). for (var prop of person)
D). forEach(prop of person)
What will console.log(obj.toString()) output?
A). The string representation of...
B). The object itself.
C). An error.
D). 1
How do you check if an object has a property 'col...
A). 'color' in obj
B). obj.hasProperty('color');
C). obj.contains('color');
D). obj.propertyExists('color');
What does the Object.values(obj) method return?
A). An array of object keys.
B). An array of object values.
C). An array of object properties.
D). An array of object methods.
How do you inherit properties and methods from a...
A). class SubClass extends SuperClas...
B). class SubClass inherits SuperCla...
C). class SubClass implements Super...
D). class SubClass derives SuperCla...
What happens if you access a non-existent property...
A). It returns undefined.
B). It throws an error.
C). It returns null.
D). It returns true.
How do you define a constructor function for crea...
A). function Car(make, model) { thi...
B). Car(make, model) { this.make = m...
C). var Car = function(make, model) ...
D). Car = function(make, model) { t...