JavaScript Arrays Quiz

To pass the quiz, you must correctly answer at least 18 of the 20 questions below. # --quizzes-- ## --quiz-- ### --question-- #### --text-- What will be the output for the following code? ```js const numbers = [1, 2, 3]; console.log(numbers[10]); ``` #### --distractors-- `[1, 2, 3]` --- `null` --- `10` #### --answer-- `undefined` ### --question-- #### --text-- Which of the following is the correct way to access the string `"Jessica"` from the `developers` array? #### --distractors-- ```js const developers = ["Jessica", "Naomi", "Tom"]; developers[1] ``` --- ```js const developers = ["Jessica", "Naomi", "Tom"]; developers[2] ``` --- ```js const developers = ["Jessica", "Naomi", "Tom"]; developers[-1] ``` #### --answer-- ```js const developers = ["Jessica", "Naomi", "Tom"]; developers[0] ``` ### --question-- #### --text-- What value will be assigned to the `index` variable? ```js const numbers = [10, 20, 30, 40]; const index = numbers.indexOf(20); console.log(index); ``` #### --distractors-- 2 --- 3 --- -1 #### --answer-- 1 ### --question-- #### --text-- What does the rest syntax do? #### --distractors-- It is used to divide a string into an array of substrings. --- It is used to add or remove elements from any position in an array. --- It is used to add elements to the end of the array and will return the new length. #### --answer-- It captures the remaining elements of an array into a new array. ### --question-- #### --text-- What is array destructuring? #### --distractors-- It is used to concatenate all of the elements of an array into a single string. --- It is used to check if an array contains a specific value. --- It is used to remove the last element from an array and will return that removed element. #### --answer-- It is used to extract values from arrays and assign them to variables in a more concise and readable way. ### --question-- #### --text-- What value will be assigned to the `arr2` variable? ```js const arr1 = [1, 2, 3]; const arr2 = [...arr1, 4, 5]; console.log(arr2); ``` #### --distractors-- `[4, 5, 1, 2, 3]` --- `[1, 2, [3, 4, 5]]` --- `[1, 2, 3]` #### --answer-- `[1, 2, 3, 4, 5]` ### --question-- #### --text-- What will this code log to the console? ```js const colors = ["red", "blue", "green", "yellow"]; colors.splice(1, 2, "purple"); console.log(colors); ``` #### --distractors-- `["red", "blue", "green", "yellow"]` --- `["red", "blue", "yellow"]` --- `["red", "yellow"]` #### --answer-- `["red", "purple", "yellow"]` ### --question-- #### --text-- What value will be assigned to the `slicedArr` variable? ```js const arr = ["apple", "banana", "cherry", "date"]; const slicedArr = arr.slice(1, 3); console.log(slicedArr); ``` #### --distractors-- `["apple", "banana"]` --- `["cherry", "date"]` --- `["apple", "cherry"]` #### --answer-- `["banana", "cherry"]` ### --question-- #### --text-- Which method returns the first index of a given element in an array? #### --distractors-- `firstIndex()` --- `lastIndex()` --- `searchIndex()` #### --answer-- `indexOf()` ### --question-- #### --text-- Which method is used to remove the first element from an array and returns that removed element? #### --distractors-- `pop()` --- `slice()` --- `splice()` #### --answer-- `shift()` ### --question-- #### --text-- What does the `concat()` method do? #### --distractors-- Joins array elements into a string. --- Adds an element to the beginning of an array. --- Removes an element from the array. #### --answer-- Merges two arrays into a new array. ### --question-- #### --text-- What will be the output of this code? ```js const fruits = ["apple", "banana", "cherry", "apple", "orange"]; fruits.splice(0, 1); console.log(fruits); ``` #### --distractors-- `["apple", "banana", "cherry", "apple", "orange"]` --- `["apple", "banana", "cherry"]` --- `["cherry", 'apple']` #### --answer-- `["banana", "cherry", "apple", "orange"]` ### --question-- #### --text-- What does the `includes()` method do? #### --distractors-- It is used to divide a string into an array of substrings. --- It is used to concatenate all of the elements of an array into a single string. --- It is used to add or remove elements from any position in an array. #### --answer-- It is used to check if an array contains a specific value. ### --question-- #### --text-- Which of the following methods is used to reverse an array in place? #### --distractors-- `reversed()` --- `reverseArr()` --- `reversing()` #### --answer-- `reverse()` ### --question-- #### --text-- What is a two dimensional array? #### --distractors-- An array that only contains object literals. --- An array of fixed length. --- An array of floating point numbers. #### --answer-- An array of arrays. ### --question-- #### --text-- Which of the following is true about the `indexOf()` method in arrays? #### --distractors-- It always returns the last occurrence of the element. --- It throws an error if the element is not found. --- It requires the array to be sorted. #### --answer-- It returns `-1` if the element is not found. ### --question-- #### --text-- Which of the following is NOT an array method? #### --distractors-- `includes()` --- `pop()` --- `push()` #### --answer-- `trim()` ### --question-- #### --text-- What will be the output for the following code? ```js const arr = ["o", "l", "l", "e", "h"]; console.log(arr.join("")); ``` #### --distractors-- `["o", "l", "l", "e", "h"]` --- `"hello"` --- `undefined` #### --answer-- `"olleh"` ### --question-- #### --text-- What will be the result of using the `shift()` method on an empty array? #### --distractors-- `TypeError` --- `[]` --- `null` #### --answer-- `undefined` ### --question-- #### --text-- Which method will return a new array without changing the original array? #### --distractors-- `shift()` --- `pop()` --- `push()` #### --answer-- `slice()`