Q
What does Object.keys(person) return if var person = {name: 'John', age: 30};?

Answer & Solution

Answer: Option A
Solution:
Object.keys(person) returns an array of the object's own enumerable property names.
Related Questions on Average

How do you access the value of the name property in the object var person = {name: 'John', age: 30};?

A). person['name']

B). person.name

C). person->name

D). person::name

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A). var obj = {};

B). var obj = [];

C). var obj = ();

D). var obj = <>;

What will console.log(newCar.make); output if class Car { constructor(make) { this.make = make; }} var newCar = new Car('Honda');?

A). Honda

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A). function Car(make, model) { this.make = make; this.model = model; }

B). Car(make, model) { this.make = make; this.model = model; }

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D). Car = function(make, model) { this.make = make; this.model = model; };

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 will the following code output? console.log(person['age']); if var person = {name: 'John'};

A). 30

B). John

C). undefined

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A). methodName() {}

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What is the output of console.log(person.greet()); if var person = {greet: function() {return 'Hello';}};?

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What will console.log(car.make); output if var car = {make: 'Toyota', model: 'Corolla'};?

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How can you check if the age property exists in the person object?

A). 'age' in person

B). person.has('age')

C). person.contains('age')

D). person.hasOwnProperty('age')