How do you define a class in JavaScript ES6?
A). class ClassName { constructor() {} }
B). function ClassName() { constructor() {} }
C). class ClassName() { constructor {} }
D). function class ClassName { constructor() {} }
What does Object.keys(obj) return?
A). An array of the values of the object's properties
B). An array of the names of the object's properties
C). The first key of the object
D). The number of properties in the object
What will car['make'] return if var car = {make: 'Ford', model: 'Mustang'};?
A). Ford
B). Mustang
C). Undefined
D). Error
How do you define a method in a constructor function?
A). this.methodName = function() {}
B). this.methodName: function() {}
C). this.methodName = () {}
D). this.methodName: () {}
What is encapsulation in the context of JavaScript objects?
A). Hiding the internal state and requiring all interaction to be performed through an object's methods
B). Extending one object from another
C). Creating a new object
D). Removing a property from an object
How do you add a new property to an existing object in JavaScript?
A). object.property = value;
B). object->property = value;
C). object:property = value;
D). object.addProperty('property', value);
How do you create a method inside an object using an object literal?
A). methodName: function() {}
B). methodName = function() {}
C). methodName: () {}
D). methodName: method() {}
Which of the following is the correct way to delete a property from an object?
A). remove object.property;
B). delete object.property;
C). delete object[property];
D). object.property = null;
How can you iterate over all properties of an object?
A). for (var key of object)
B). for (var key in object)
C). for (var key with object)
D). for (var key over object)
How do you define a method inside a class in JavaScript ES6?
A). methodName() {}
B). this.methodName = function() {}
C). function methodName() {}
D). methodName: function() {}