Library

Converts a given date to a time string

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

Implement a function that uses String's padStart method to add leading zeros to a number string to ensure it always has a minimum length

Create a function that takes in a string and checks if it starts with a given substring. Return a boolean indicating whether or not the string starts with the given substring.

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

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

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

This kata focuses on using String.prototype.indexOf() method.

Create a function that takes a year (YYYY) and returns the date object with its year set to the provided year.

Create a function that returns an array of values of an array using the Array.prototype.values() method.

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

Write a function that uses recursion to calculate the factorial of a given positive integer.

Use Array.prototype.slice() to solve the following tasks.

Create a function that returns the month of a Date object in UTC time zone.

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

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

Create an Inventory Management System that allows users to add, remove and update items in the inventory.

Given a date, return the UTC date.

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.

Convert an array to a string with comma-separated values. The input array can contain numbers, strings, objects, or arrays.

Create a function that takes an array of numbers and returns the index of a given element. Use Array.prototype.findIndex() to implement the function.

Create a function that takes in an array of music tracks and returns an object with the count of each genre in the array

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

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

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

Implement an algorithm that manages the overbooking of an airline flight.

Create a function that takes a string and a number as arguments, and pads the string on the right side with spaces until the string reaches the desired length.

Create a function that takes a start time and an event duration and returns the end time of the event, using the Date.prototype.setHours() method to set the hours of the start time.

Implement a function that takes a Date object as input and returns a formatted string

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

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

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

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

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

Implement normalize method to format a string removing all the accents

Write a function that checks if a given variable is an array. If it is an array, return true, otherwise return false.

Implement a function that returns the current month from Date object using Date.prototype.getMonth()

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

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.

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

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

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.

Implement various functionalities using Array.prototype.slice() method

Write a function that returns the result of a string match with a given pattern.

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.

Given an array of numbers, use reduce method to obtain a single value that represents the sum of all numbers in the array.

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

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

Implement a function that returns true if a given string starts with a specific substring.

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

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

Create a function that takes two parameters: a string and a regular expression. The function should return an array of all matches found in the string using the regular expression.

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 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.

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

Create a function that repeats a given string n times.

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 takes a string and a regular expression and returns an array of all the substrings in the string that match the regular expression.

Write a function that takes a Set object as a parameter and returns an array of keys using Set.prototype.keys().

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 string as input and converts it to a UTC date string format.

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 two parameters, a string and a substring, and checks if the string includes the substring. Return a boolean value.

Write a function that takes two arrays as arguments and concatenates them into a new array using the Array.prototype.concat() method.

Given a sentence, split it into an array of words using the String.prototype.split() method.

Write a function that takes a date object and a number representing the desired month, and sets the month of the date to the given month.

Create a function that takes an array and removes a portion of the array, as specified by the arguments, and returns the removed portion.

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

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.

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

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

Create a function that accepts a string and a target length. If the length of the string is less than the target length, pad the string with spaces at the beginning until the target length is reached. If the string length is greater than or equal to the target length, return the original string.

Create a function that receives a string and a regular expression pattern and returns an array of all the occurrences of the pattern in the string using String.prototype.matchAll().

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

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

Create a function that takes an array and reverse its order in place.

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

Write a function that takes a string and a substring as arguments, and finds the last occurrence of the substring in the string. If the substring is not found, return -1.

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

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

Complete the functions to find the index of an element in an array using Array.prototype.indexOf().

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

Create a function that concatenates two strings using the String.prototype.concat() method. The function should take two string parameters and return the concatenated string.

Create a function that takes in a string and uses String.prototype.match() to find all occurrences of a pattern within the string.

Create a function that takes a string and a number, and repeats the string the given number of times.

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.

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

Implement a function that takes an array of strings and a search string, and returns a new array containing only the strings that includes the search string using String.prototype.includes() method.

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

Write a function that checks if a given string has a unicode character code point greater than or equal to 128. Use the String.prototype.codePointAt() method.

Create a function that transforms a given string to uppercase, using String.prototype.toLocaleUpperCase()

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

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

Create a function that takes two strings as input and concatenates them using the String.prototype.concat() method.

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.

Create a function that takes an array as input and returns a new array with the elements in reversed order.

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

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