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
How can you check if a property exists in an object?
A). 'property' in object
B). object.hasProperty('property')
C). object.contains('property')
D). object.includes('property')
What does Object.assign(target, ...sources) do?
A). Copies properties from sources to target
B). Compares properties between target and sources
C). Deletes properties in sources
D). Merges properties of sources into target and removes duplicates
How do you define a method inside a class in JavaScript ES6?
A). methodName() {}
B). this.methodName = function() {}
C). function methodName() {}
D). methodName: function() {}
Which method can be used to call a function defined within an object?
A). object.functionName();
B). object->functionName();
C). object::functionName();
D). object.callFunction('functionName');
What is the output of car.start() if var car = {start: function() {console.log('Car started');}};?
A). Car
B). started
C). Car started
D). Error
How do you create a method inside an object using an object literal?
A). methodName: function() {}
B). methodName = function() {}
C). methodName: () {}
D). methodName: method() {}
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 class in JavaScript ES6?
A). class ClassName { constructor() {} }
B). function ClassName() { constructor() {} }
C). class ClassName() { constructor {} }
D). function class ClassName { constructor() {} }
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;