Javascript Algorithms and Data Structures

What is the purpose of the "keys" method in JavaScript objects?

• It returns an array of all values in the object.
• It returns an array of all properties in the object.
• It returns an array of all property names in the object.
• It returns an array of all methods in the object.

What method joins two arrays together?

• concat

How can you implement a matrix in javascript?

• an array of arrays

Which of the following is NOT a valid way to create a function in JavaScript?

• function myFunction() {}
• myFunction = function() {};
• const myFunction = () => {};
• myFunction = () => {};

Which of the following is NOT a valid primitive data type in JavaScript?

• Boolean
• Date
• Number
• String

What is another name for a two-dimensional array?

• matrix

Which of the following is used to declare a constant variable in JavaScript?

• const
• let
• var

Which of the following is true about the "break" statement in JavaScript?

• It is used to exit a function.
• It is used to skip the current iteration of a loop and move to the next one.
• It is used to terminate the execution of a loop or switch statement.
• It is used to catch and handle errors in a try-catch block.

In JavaScript, what is the purpose of the "map" method for arrays?

• It creates a new array with all elements that pass a certain test.
• It creates a new array by performing a specified action on each element of the original array.
• It returns the first element of the array.
• It combines two arrays into a single array.

What does the acronym DOM stand for in the context of web development?

• Document Object Model
• Dynamic Order Management
• Digital Output Mode

What does the "split" method do in JavaScript?

• It joins elements of an array into a single string.
• It divides a string into an array of substrings based on a specified separator.
• It replaces a substring in a string with another substring.
• It removes all occurrences of a specified substring from a string.

What does the "typeof" operator return when applied to an array in JavaScript?

• "object"
• "array"
• "array-like"

What is the purpose of the "return" statement in a JavaScript function?

• It specifies the value that the function should output.
• It terminates the execution of the function immediately.
• It defines a variable with a specific value.
• It declares a loop within the function.

What does the "push" method return after adding an element to an array?

• The new length of the array
• The added element
• The updated array
• The index of the added element

Which statement is used to exit or "break" out of a loop in JavaScript?

• return
• break
• exit

What array method allows us to remove an element in the beginning of an array?

• shift

What stores a sequence of values that are all of the same data type?

• array

Which of the following is used to round a number up to the nearest integer in JavaScript?

• round()
• Math.ceil()
• Math.floor()
• Math.roundUp()

What does the "splice" method do in JavaScript?

• It removes an element from the end of an array.
• It allows you to add or remove elements from a specific position in an array.
• It reverses the order of elements in an array.
• It returns a shallow copy of an array.

Which of the following is NOT a valid loop in JavaScript?

• repeat loop
• for loop
• while loop
• do...while loop

What is the purpose of the "concat" method for arrays in JavaScript?

• It combines two arrays into a single array.
• It combines two or more arrays and returns a new array.
• It creates a copy of an array.
• It adds an element to the beginning of an array.

What is the purpose of the "parseFloat" function in JavaScript?

• It converts a string to a floating-point number.
• It converts a number to a string.
• It rounds a floating-point number to the nearest integer.
• It returns the fractional part of a number.

What is the purpose of the "push" method in JavaScript arrays?

• It removes the last element from the array.
• It adds a new element to the beginning of the array.
• It adds a new element to the end of the array.
• It reverses the order of the elements in the array.

What is the purpose of the "find" method for arrays in JavaScript?

• It checks if any element in the array passes a certain test defined by a provided function.
• It returns the index of the first element that passes a certain test.
• It returns the first element in the array that passes a certain test defined by a provided function.
• It removes all elements that pass a certain test from the array.

Which built-in JavaScript function is used to round a number to the nearest integer?

• round()
• Math.round()
• floor()
• ceil()

What does the "length" property of an array in JavaScript represent?

• The number of elements in the array
• The sum of the values of all elements in the array
• The average value of the elements in the array

Which of the following is a valid way to create a new object in JavaScript?

• newObject = Object.create();
• newObject = {};
• newObject = new Object();
• newObject = Object.new();

What do the shift and unshift methods allow an array to emulate?

• queue

What does the term "hoisting" refer to in JavaScript?

• The process of elevating a function call to the top of the call stack
• The behavior of moving variable and function declarations to the top of their containing scope during compilation
• A way to optimize asynchronous code execution
• The process of converting data types automatically

Which data structure follows the "Last In, First Out" (LIFO) principle?

• Queue
• Linked List
• Stack
• Hash Table

Which of the following methods is used to convert a string to uppercase in JavaScript?

• toUpper()
• upper()
• toUpperCase()
• uppercase()

What does the term "asynchronous" mean in the context of JavaScript?

• It refers to code that doesn't necessarily execute in a linear, top-to-bottom order, allowing other code to run in the meantime.
• It describes code that only runs on alternate days.
• It refers to code that executes instantly without any delay.
• It describes code that runs only when the browser is offline.

What is the purpose of the "isNaN" function in JavaScript?

• It checks if a variable is of the data type "NaN".
• It checks if a value is "Not-a-Number".
• It converts a value to the data type "NaN".
• It checks if a value is null or undefined.

What is the main difference between "==" and "===" in JavaScript?

• "==" performs a strict equality comparison, while "===" performs a loose equality comparison.
• "==" compares values and types, while "===" only compares values.
• "==" performs type coercion, while "===" requires both values to be of the same type.
• There is no difference; "==" and "===" are interchangeable.

Which method is used to remove the first element from an array in JavaScript?

• shift()
• removeFirst()
• deleteFirst()

What does the "splice" method return after removing elements from an array?

• An array containing the removed elements
• The index of the first removed element
• The number of elements removed
• The updated array with the elements removed

What does the "charAt" method return when passed an index that is out of range in a string?

• An empty string
• null
• undefined
• An error message

What does the "toUpperCase" method do in JavaScript?

• It converts a string to uppercase.
• It converts a string to lowercase.
• It checks if a string contains only uppercase characters.
• It removes all whitespace from a string.

Which keyword is used to declare a function in JavaScript?

• func
• function
• method

What does the "isNaN" function return when passed an empty string ("")?

• false
• true
• null
• undefined

What is the purpose of the "filter" method for arrays in JavaScript?

• It removes elements from the array that meet a certain condition.
• It creates a new array with all elements that pass a certain test defined by a provided function.
• It returns the index of the first element that passes a certain test.
• It sorts the elements of the array in ascending order.

What is the purpose of the "shift" method in JavaScript arrays?

• It adds a new element to the beginning of an array.
• It removes the first element from an array.
• It reverses the order of elements in an array.

What is a data structure where we can have rows and columns?

• two-dimensional array

What does the "isNaN" function return when passed the value "undefined"?

• true
• false
• null
• undefined

Which of the following is used to add a comment within an HTML file that won't be visible on the webpage?

• <!~Hasdoublearr~ This is a comment ~Hasdoublearr~>
• // This is a comment
• /* This is a comment */

Which of the following is used to store and manage key-value pairs in JavaScript?

• Array
• List
• Object
• Tuple

What does the term "closure" refer to in JavaScript?

• A function that has no return statement.
• A function that retains access to its outer function's variables even after the outer function has finished executing.
• A function with no parameters.
• A function that can only be called once.

What does the "typeof" operator in JavaScript return?

• The data type of a variable
• A string indicating the data type of a value
• The memory address of a variable
• The size of an object

What is the purpose of the "every" method for arrays in JavaScript?

• It checks if all elements in an array pass a certain test defined by a provided function.
• It adds a new element to the beginning of an array.
• It removes elements from the array that meet a certain condition.
• It combines two arrays into a single array.

What does the "isNaN" function return when passed the value "null"?

• false
• true
• null

Which of the following methods is used to remove the last element from an array in JavaScript?

Which of the following is used to declare a global variable in JavaScript?

• var
• global
• let

Which of the following is a valid way to comment a single line of code in JavaScript?

• // This is a comment
• /* This is a comment */
• <!~Hasdoublearr~ This is a comment ~Hasdoublearr~>

What is the purpose of the "Math.random" function in JavaScript?

• It generates a random floating-point number between 0 (inclusive) and 1 (exclusive).
• It generates a random integer between 0 and a specified maximum value.
• It generates a random number between a specified minimum and maximum value.
• It generates a random boolean value.

What is the purpose of the "startsWith" method in JavaScript?

• It checks if a string starts with a specified substring.
• It returns the index of the first occurrence of a substring in a string.
• It replaces the first occurrence of a substring with another substring in a string.
• It removes the first character from a string.

Which of the following is a comparison operator in JavaScript?

• &
• ==
• ><

What does the "push" method do in JavaScript when applied to a string?

• It adds a new character to the beginning of the string.
• It adds a new character to the end of the string.
• It removes the last character from the string.
• It replaces a specified character with another character in the string.

Which keyword is used to declare a constant variable in JavaScript?

• const
• let
• var

Which of the following is true about the "continue" statement in JavaScript?

• It is used to skip the current iteration of a loop and move to the next one.
• It is used to exit a loop.
• It is used to catch and handle errors in a try-catch block.
• It is used to restart the loop from the beginning.

What is the purpose of the "Math.max" function in JavaScript?

• It returns the largest of zero or more numbers.
• It returns the smallest of zero or more numbers.
• It rounds a number to the nearest integer.
• It calculates the absolute value of a number.

What is the purpose of the "join" method for arrays in JavaScript?

• It combines all the elements of an array into a single string, using a specified separator.
• It adds a new element to the end of the array.
• It removes all occurrences of a specific element from the array.
• It reverses the order of elements in the array.

What does the "lastIndexOf" method do in JavaScript?

• It returns the index of the last occurrence of a specified substring in a string.
• It returns the index of the first occurrence of a substring in a string.
• It checks if a specific substring is present in a string.
• It removes the last occurrence of a specified substring from a string.

What is the role of the "else" statement in an "if-else" construct?

• It defines a new condition to be checked if the first "if" condition is false.
• It provides an alternative code block to be executed if the initial "if" condition is false.
• It marks the end of the "if" statement.
• It is used to create a loop.

What is the purpose of the "Date" object in JavaScript?

• It represents a specific moment in time and provides methods for working with dates and times.
• It creates an array of date-related functions.
• It formats strings in a date-like format.
• It returns the current time in milliseconds.

What does the "indexOf" method return when the searched element is not found in an array?

• -1
• 0
• null

What array method allows us to insert an element in the beginning of an array?

• unshift

Which built-in method is used to sort elements in an array in JavaScript?

• order()
• sort()
• arrange()

What is the primary difference between "null" and "undefined" in JavaScript?

• "null" is a value that represents the intentional absence of any object value, while "undefined" indicates a variable that has been declared but hasn't been assigned a value.
• They are interchangeable and can be used in the same contexts.
• "undefined" is a value that represents the intentional absence of any object value, while "null" indicates a variable that has been declared but hasn't been assigned a value.
• "null" is a reserved keyword, while "undefined" is not.

What array method allows us to add an element to the end?

• push

Which function is used to convert a JSON string into a JavaScript object?

• parseJSON()
• JSON.parse()
• fromJSON()
• stringifyJSON()

Which of the following is the correct way to declare a multi-dimensional array in JavaScript?

• var matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
• var matrix = {1, 2, 3; 4, 5, 6; 7, 8, 9};
• var matrix = [1, 2, 3][4, 5, 6][7, 8, 9];
• var matrix = new Array[1, 2, 3][4, 5, 6][7, 8, 9];

What is the purpose of the "reverse" method for arrays in JavaScript?

• It sorts the elements of an array in descending order.
• It reverses the order of elements in an array.
• It removes the last element from an array.
• It adds a new element to the beginning of an array.

Which of the following is used to create a new array by applying a function to each element of an existing array?

• map()
• filter()
• reduce()
• forEach()

Which of the following is NOT a valid way to declare a string in JavaScript?

• string myString = "Hello";
• var myString = "Hello";
• const myString = "Hello";
• let myString = "Hello";

What array method allows us to remove an element by simply specifying the position/index, and how many elements we would like to remove?

• splice

What does the "splice" method do in JavaScript when used with only one argument?

• It removes a specified number of elements from an array, starting from the beginning.
• It removes a specified number of elements from an array, starting from the specified index.
• It adds a new element to the beginning of an array.
• It adds a new element to the end of an array.

What is the purpose of the "reduce" method for arrays in JavaScript?

• It adds up all the elements of the array.
• It creates a new array by applying a function to each element.
• It reduces the array to a single value by applying a function to each element and accumulating the result.
• It removes elements from the array that meet a certain condition.

What does the "substr" method do in JavaScript?

• It returns a new string with a specified number of characters removed from the beginning.
• It returns a new string with a specified number of characters removed from the end.
• It returns a substring of a string, starting at a specified position and ending at the specified position.

What is the output of the following code snippet? console.log(2 + "2");

• 22
• 4
• "22"

Which type of loop is guaranteed to execute at least once?

• while loop
• do...while loop
• for loop
• if loop

What is the purpose of the "concat" method in JavaScript when used with strings?

• It combines two or more strings and returns a new string.
• It adds a new character to the end of a string.
• It replaces a substring with another substring in a string.
• It checks if a string contains a specific substring.

Which operator is used to compare two values for equality in JavaScript?

• ==
• =
• !=

What does the "toLowerCase" method do in JavaScript?

• It converts a string to lowercase.
• It checks if a string contains only lowercase characters.
• It converts a string to uppercase.
• It removes all whitespace from a string.

Which of the following is a valid way to define a function with parameters in JavaScript?

• function myFunction(parameter1, parameter2) {}
• const myFunction = parameter1, parameter2 => {}
• myFunction = function(parameter1, parameter2) {}

Which of the following is used to perform asynchronous programming in JavaScript?

Which of the following is NOT a valid way to declare a variable in JavaScript?

• var myVar = 10;
• let anotherVar = "Hello";
• const PI = 3.14;
• variable myVar = 10;

What is the purpose of the "unshift" method in JavaScript arrays?

• It removes the first element from an array.
• It adds a new element to the beginning of an array.
• It adds one or
• more elements to the beginning of an array and returns the new length.
• It reverses the order of elements in an array.

What does the "trim" method do in JavaScript?

• It removes whitespace from both ends of a string.
• It adds whitespace to both ends of a string.
• It removes all occurrences of a specific character from a string.
• It converts a string to uppercase.

Which of the following is used to create an empty object in JavaScript?

• new object()
• {}
• emptyObject()
• object = Object.create()

Which of the following is used to remove the first element from an array in JavaScript?

• removeFirst()
• shift()
• pop()

What does the "charAt" method do in JavaScript?

• It removes the character at a specified position in a string.
• It returns the character at a specified position in a string.
• It checks if a specific character is present in a string.
• It adds a new character to the end of a string.

What is the purpose of the "toLocaleString" method in JavaScript?

• It returns a string representing the object's value, formatted according to the conventions of the current locale.
• It converts a string to lowercase and returns it.
• It converts a number to a currency format and returns it as a string.
• It checks if a string contains only lowercase characters.

What is the purpose of the "Math.pow" function in JavaScript?

• It returns the square root of a number.
• It returns the result of raising a number to a specified power.
• It rounds a number to the nearest integer.
• It calculates the absolute value of a number.

What does the "pop" method return when called on an empty array?

• null
• undefined
• 0

What is the purpose of the "charAt" method in JavaScript?

• It returns the character at a specified index in a string.
• It removes the character at a specified index in a string.
• It adds a new character at the end of a string.
• It checks if a specific character is present in a string.

Which of the following is used to add a new element to the end of an array in JavaScript?

• add()
• push()
• append()
• insert()

Which operator is used to access a property or method of an object in JavaScript?

• .
• ,
• ::
• ;

What does the "toFixed" method do in JavaScript?

• It formats a number with a specified number of decimal places and returns it as a string.
• It rounds a number to the nearest integer and returns it as a string.
• It converts a number to a fixed notation.
• It returns the fractional part of a number as a string.

What is the purpose of the "length" property of a string in JavaScript?

• It returns the number of characters in the string.
• It returns the last character of the string.
• It returns the first character of the string.
• It returns the sum of the Unicode values of all characters in the string.

What does the "pop" method do in JavaScript?

• It removes the first element from an array.
• It removes the last element from an array.
• It removes all elements with a specific value from an array.

What is the purpose of the "Math.floor" function in JavaScript?

• It rounds a number down to the nearest integer.
• It rounds a number up to the nearest integer.
• It rounds a number to the nearest integer.
• It returns the smallest integer greater than or equal to a number.

Which statement is used to catch and handle errors in JavaScript?

• try
• error
• catch
• handle

Which of the following is used to remove the last element from an array in JavaScript?

• pop()
• shift()
• removeLast()
• deleteLast()

What does the "NaN" acronym stand for?

• Not a Normal number
• Not a Number
• No available Number
• Null and None

What array method allows us to remove an element in the end of an array?

• pop

What array method will iterate each element of the array until the return of the function is false?

• every

Which of the following is a valid way to access the value of a property in a JavaScript object?

• object.property
• object[property]
• object->property

What does the "charAt" method return when passed a negative index in a string?

• An empty string
• null
• undefined
• An error message

What is the purpose of the "slice" method for arrays in JavaScript?

• It removes the last element from an array.
• It returns a copy of a portion of an array, selected by specifying starting and ending indices.
• It adds elements to an array based on a specified range.

What is the purpose of the "typeof" operator when used with the "function" keyword?

• It returns "function" when applied to a function.
• It checks if a variable is a function.
• It returns the name of the function.
• It returns the parameters of the function.

What is the role of the "continue" statement in a loop?

• It terminates the loop and resumes execution from the beginning of the loop.
• It skips the current iteration of the loop and continues with the next iteration.
• It exits the loop immediately.
• It restarts the loop from the beginning.