Library

Create a function that takes an array as input and returns an array of the keys of the given array using Array.prototype.keys() method.

Create a function that concatenates two strings using the String.prototype.concat() method.

Write a function that converts a given string to its string representation using the toString() method.

Write a function that takes a string as input and splits it into an array of words using String.prototype.split(). Then, join the array back into a string using Array.prototype.join(). Finally, return the new string with a different delimiter separating each word.

Create a function that takes a Date object and returns a JSON string of the date in ISO format.

Write a function that flattens nested arrays using Array.prototype.flat() method.

Write a function that takes an array of numbers and returns their sum, using Array.prototype.reduceRight().

Create a function that takes a string as input and returns the string in all lowercase letters.

Given an array of numbers and a start index, remove a certain number of elements from the array and replace them with new elements.

Create a function that takes in a string with extra white space at the beginning and end of the string, and returns a new string with that white space removed. Use String.prototype.trim().

Create a Stock Advisor that recommends which stocks to buy based on certain parameters.

Write a function that takes a date string as input and converts it to a UTC date string format.

Write a function that concatenates two strings using the String.prototype.concat() method.

Convert a string to uppercase using String.prototype.toUpperCase();

Implement a function that adds a value to a set using Set.prototype.add().

Create a function that uses Array.prototype.entries() to iterate over an array and perform some operations.

Implement a function that takes in a Set and returns an array of entries

Create a function that uses Array.prototype.every() to check if all the elements in an array meet a certain condition.

Implement a function that removes leading and trailing whitespace from a string using the String.prototype.trim() method.

Write a function that takes a Date object and returns the date formatted in the user's local format using the toLocaleDateString() method.

Write a function that takes a string and returns all its substrings of length 3 or greater. You must use String.prototype.slice() to achieve this.

Write a function that converts a given string to uppercase

Fill arrays with specific values using Array.prototype.fill()

Write a function that returns an array of char codes from a string

Implement a function that groups an array of objects by a given key and returns a new array of objects, where each object has a key and an array of objects that have that key.

Write a function that takes a string and regular expression as inputs, and returns an array of all matches found using the String.matchAll() method.

Create a function that repeats a given string n times.

Implement the Array.prototype.unshift() method without using built-in functions

Create a function that takes in two parameters, a string and a substring, and checks if the string includes the substring. Return a boolean value.

Implement a function that returns the character at the specified index of a given string.

Create a function that takes a string and returns an array of the char codes for each character in the string

Write a function that takes an array and a value as arguments and returns the index of the last occurrence of that value in the array using Array.prototype.lastIndexOf(). If the value is not found, return -1.

Write a function that returns the nth number in the Fibonacci sequence using recursion.

Create a function that sorts an array of strings in alphabetical order using String.prototype.localeCompare()

Write a function that takes an integer n and returns the nth Fibonacci number using recursion.

Converts a given date to a time string

Implement a function that concatenates a given string 'n' times using the String.prototype.repeat() method.

Create a function that takes an array and a value as arguments and adds the value to the beginning of the array using the unshift() method.

Write a function that returns the index of the first occurrence of a given element in an array using Array.prototype.indexOf(). If the element is not found in the array, return -1.

Create a function that receives a Date object and returns the milliseconds that have elapsed since the start of the day.

Convert a string to an array of Unicode code points using String.prototype.codePointAt() method.

Write a function that returns whether a given string ends with the provided suffix or not

Given an array of objects, group the objects based on a specific key and return a map object.

Write a function that returns the value of a given string using the String.prototype.valueOf() method.

Write a function that accepts a date object and a number of seconds (0 - 59) and returns a new date object with the seconds set to the provided value. The operation should be done using the setUTCSeconds() method.

Create a function that sets the UTC month of a given date object.

Implement normalize method to format a string removing all the accents

Create a function that counts the number of seconds in a given timestamp

Write a function that takes a string and returns an array of matched patterns using String.prototype.matchAll().

Write a function that takes in a date and returns the seconds within the minute in UTC time.

Create a function that takes a string and returns a new string that is a slice of the original string. The function should take two arguments, start and end, which represent the starting and ending indices of the slice.

Create a function that returns the current minutes.

Write a function that accepts a string and a number as arguments, then returns the character at that position in the string. Use String.prototype.charAt() for this exercise.

Write a function that takes in a string and a target substring, and returns the index at which the target substring is first found. If the target substring is not found in the string, return -1. Use the built-in JavaScript method `indexOf()` to solve the problem.

Create a function that replaces all instances of a given substring with another string within a larger string using String.prototype.replaceAll() method.

Create a function to search for a substring in a given string using String.prototype.search() method.

Create a function that will return an array in a localized way using the toLocaleString method.

Sort an array of words based on their alphabetical order using String.prototype.localeCompare() method.

Create a function that takes a date and a year as arguments and returns a new date with the year set to the specified value using Date.prototype.setFullYear().

Write a function that takes a date and returns the year in the hh:mm:ss format.

Implement a function that groups the elements of an array based on a given predicate function.

Create a function that receives a string and a number as parameters. The function should return the string repeated `n` times, where n is the number passed as parameter.

Combine two arrays into a single array using the Array.prototype.concat() method

Create a function that receives a string and a number n, the function should return the string repeated n times.

Create a function that accepts a Set and a value to remove, and returns the updated Set after deleting the value.

Create a function that uses Array.prototype.findLast() to find the last element in an array that matches a given condition. Return the element if it exists or null if it does not.

Implement the Array.prototype.with() method that returns a new array with the elements from the original array and the added elements.

Given an array of person objects, sort them alphabetically by their last name using String.prototype.localeCompare().

Write a function that checks if every element in an array satisfies a given condition.

Write a function that uses the String.prototype.trimStart() method to remove any whitespace characters from the beginning of a given string.

Write a function that takes a string and a substring, and returns the index of the first occurrence of the substring in the string. If the substring is not found in the string, return -1.

Write a function that loops through a Set using Set.prototype.forEach() method and returns an array containing the results of applying the provided function to each element.

Create a function that returns the current year using Date's built-in getFullYear method

Implement a function that replaces all instances of a specified substring in a given string.

Create a function that takes a date and a year and sets the date's UTC full year to the provided year.

Create a function that normalizes a string using String.prototype.normalize method.

Write a function that normalizes a string using String.prototype.normalize().

A kata that requires the student to use String.prototype.split() to split a given string into substrings and perform a specified operation on them.

Given a date, return the UTC date.

Create a function that searches for the last index of a substring in an array using Array.prototype.lastIndexOf().

Implement a function that takes a Date object and a number representing minutes and sets the UTC minutes of the Date object to the provided value. The function should return the updated Date object.

Write a function that joins two arrays into a single string using Array.prototype.join() method.

Write a function that takes a string and returns it in lowercase using the toLocaleLowerCase() method.

Implement a function that sets the milliseconds of a given date object to a specified value.

Create a function that uses the String.prototype.replaceAll() method to replace all occurrences of a given substring within a string.

Implement equations using the Array.of() method to create arrays.

Write a function that checks whether a given string ends with the specified suffix or not.

Write a function that returns a substring of a given string, starting at a specified index and ending before a specified index.

Write a JavaScript function to find the index of an item in an array using Array.prototype.findIndex().

Write a function that checks if a given string includes a specific substring. Use String.prototype.includes() method.

Given a string, return a new string that is a substring of the original string. The substring should start at a specified index and continue until the end of the original string.

Implement a function that removes all unused items in a Set collection

Implement a function that uses String.prototype.trimEnd() to trim whitespace at the end of a string.

Create a program that classifies music genres based on certain audio features

Create a function that uses the copyWithin method to replace specified elements within an array.

Write a function that takes an array and a value and pushes the value to the end of the array using Array.prototype.push().

Create a function that greets the user depending on the current hour of the day.

Create a function that checks if a given string ends with a specified suffix.

Write a function that takes a date object and a number of seconds and returns a new date object with the seconds set to the provided value. Example input: setSeconds(new Date('2022-10-10T10:10:10'), 30) Expected output: new Date('2022-10-10T10:10:30')

Write a function that checks if an element is present in an array using Array.prototype.includes() method.