JavaScript Objects Quiz

To pass the quiz, you must correctly answer at least 18 of the 20 questions below. # --quizzes-- ## --quiz-- ### --question-- #### --text-- Which of the following does NOT describe an object in JavaScript? #### --distractors-- A collection of key-value pairs. --- A container for properties and methods. --- A non-primitive data type. #### --answer-- A primitive data type. ### --question-- #### --text-- Which of the following object definitions is invalid? #### --distractors-- `const book = { "pages": 255 };` --- `const car = { year: 2025 };` --- `const person = { "name": "nora" };` #### --answer-- `const product = { color: blue };` ### --question-- #### --text-- How can you access the `job` property of this `person` object? ```js let person = { job: "Software Developer" }; ``` #### --distractors-- `person -> job` --- `person#job` --- `person[job]` #### --answer-- `person.job` ### --question-- #### --text-- How can you access the `street` property of the `person` object below? ```js const person = { address: { street: "sample-street" } }; ``` #### --distractors-- `person -> address -> street` --- `person#address#street` --- `person[address.street]` #### --answer-- `person["address"]["street"]` ### --question-- #### --text-- Which of these property keys can only be accessed using bracket notation? #### --distractors-- A property key that is known and static. --- A property key that is nested within multiple levels of an object. --- A property key that might not exist in the object. #### --answer-- A property key that is dynamic. ### --question-- #### --text-- Which of the following correctly uses destructuring to access the `name` property of the `person` object below? ```js const person = { name: "John" } ``` #### --distractors-- `const name = person.name;` --- `const name = person["name"];` --- `const { ...name } = person;` #### --answer-- `const { name } = person;` ### --question-- #### --text-- Which of the following correctly uses destructuring to access the `flour` property of the `recipe` object below? ```js const recipe = { ingredients: { flour: "2 cups", sugar: "1 cup" } }; ``` #### --distractors-- `const flour = recipe.ingredients.flour;` --- `const flour = recipe["ingredients"]["flour"];` --- `const { ingredients: flour } = recipe;` #### --answer-- `const { ingredients: { flour } } = recipe;` ### --question-- #### --text-- How can you assign a default value to a property key when using destructuring in JavaScript? #### --distractors-- `const key = object.key && "defaultValue";` --- `const key = object.key || "defaultValue";` --- `const { key: "defaultValue" } = object;` #### --answer-- `const { key = "defaultValue" } = object;` ### --question-- #### --text-- How can you check if a `car` object has a `year` property? #### --distractors-- `year.hasProperty("car");` --- `car.hasProperty("year");` --- `car.hasOwnProperty(year);` #### --answer-- `car.hasOwnProperty("year");` ### --question-- #### --text-- What is an object method? #### --distractors-- A string associated with an object. --- An array associated with an object. --- A number associated with an object. #### --answer-- A function associated with an object. ### --question-- #### --text-- How can you call the `add` method of this `calculator` object to add the numbers `10` and `7`? ```js const calculator = { add: function(a, b) { return a + b; } }; ``` #### --distractors-- `calculator#add(10, 7);` --- `calculator.call(add(10, 7));` --- `add.calculator(10, 7);` #### --answer-- `calculator.add(10, 7);` ### --question-- #### --text-- Which operator removes a property from an object? #### --distractors-- `remove` --- `erase` --- `discard` #### --answer-- `delete` ### --question-- #### --text-- How can you check if a `score` property exists in a `player` object? #### --distractors-- `player in "score"` --- `player in score` --- `score in player` #### --answer-- `"score" in player` ### --question-- #### --text-- How can you create a new empty object in JavaScript? #### --distractors-- `object() new` --- `new object()` --- `Object() new` #### --answer-- `new Object()` ### --question-- #### --text-- What is the correct syntax for using optional chaining in JavaScript? #### --distractors-- `object?key` --- `object.["key"]` --- `object.?key` #### --answer-- `object?.key` ### --question-- #### --text-- What is optional chaining used for in JavaScript? #### --distractors-- Used to define variables with default values. --- Used to define optional methods within an object that may or may not be called. --- Used to write more concise code by chaining multiple method calls together in a single statement. #### --answer-- Used to safely access properties of an object that might be `null` or `undefined`. ### --question-- #### --text-- What method is used to convert a JavaScript object into a JSON string? #### --distractors-- `Stringify.toJSON()` --- `JSON.toObject()` --- `Object.toJSON()` #### --answer-- `JSON.stringify()` ### --question-- #### --text-- What method converts a JSON string back into a JavaScript object? #### --distractors-- `JSON.toObject()` --- `JSON.convert()` --- `JSON.object()` #### --answer-- `JSON.parse()` ### --question-- #### --text-- Which one of these options accesses the `color` property of a `toy` object using bracket notation? #### --distractors-- `toy.color` --- `toy[color]` --- `color[toy]` #### --answer-- `toy["color"]` ### --question-- #### --text-- How can you access the `home` phone of this `learner` object in JavaScript using dot notation? ```js const learner = { name: "Nora", age: 45, contact: { email: "nora@email.com", phone: { home: "123-456-7890", work: "098-765-4321" } } }; ``` #### --distractors-- `learner.name.phone.home` --- `learner.email.work` --- `learner.contact.home` #### --answer-- `learner.contact.phone.home`