JavaScript Practice Exercises with Employee Data This repository contains JavaScript exercises designed to improve your problem-solving skills using an employee dataset. The exercises focus on manipulating and analyzing employee data using fundamental JavaScript concepts like loops, conditions, string manipulation, object manipulation, and arrays.

Constraints:

You are not allowed to use map, filter, reduce, or Object.keys/Object.values/Object.entries Only use for, while, and standard logic Focus on the provided employees array object Table of Contents Easy Basic Data Retrieval Simple Calculations Medium Employee Data Analysis Department Operations Project Operations Advanced Complex Data Transformations Statistical Analysis Search and Grouping Easy Easy - Basic Data Retrieval Get the first name of the first employee

Function Name: getFirstEmployeeFirstName Input: employees Output: "Jean" Expected Result: Returns the first name of the first employee in the array. Get the last name of the last employee

Function Name: getLastEmployeeLastName Input: employees Output: "Leroy" Expected Result: Returns the last name of the last employee in the array. Get the department of employee with ID 5

Function Name: getEmployeeDepartmentById Input: employees, 5 Output: "Marketing" Expected Result: Returns the department of the employee with ID 5. Count how many employees are in the array

Function Name: countEmployees Input: employees Output: 50 Expected Result: Returns the total number of employees in the array. Check if any employee is inactive (isActive: false)

Function Name: hasInactiveEmployees Input: employees Output: true Expected Result: Returns true if any employee is inactive, otherwise false. Easy - Simple Calculations Calculate the average age of all employees

Function Name: calculateAverageAge Input: employees Output: 31.2 Expected Result: Returns the average age of all employees. Find the employee with the highest salary

Function Name: getHighestPaidEmployee Input: employees Output: { id: 34, firstName: "Paul", lastName: "Leclercq", ... } Expected Result: Returns the employee object with the highest salary. Count how many employees are in the "Développement" department

Function Name: countEmployeesInDepartment Input: employees, "Développement" Output: 15 Expected Result: Returns the number of employees in the "Développement" department. List all unique department names

Function Name: getUniqueDepartments Input: employees Output: ["Développement", "Design", "Management", "Marketing"] Expected Result: Returns an array of unique department names. Check if any employee has no projects assigned

Function Name: hasEmployeesWithoutProjects Input: employees Output: true Expected Result: Returns true if any employee has no projects assigned, otherwise false. Medium Medium - Employee Data Analysis Count how many employees speak English

Function Name: countEnglishSpeakingEmployees Input: employees Output: 45 Expected Result: Returns the number of employees who speak English. Find all employees who work on "Project Gamma"

Function Name: getEmployeesByProject Input: employees, "Project Gamma" Output: [ { id: 1, firstName: "Jean", ... }, { id: 2, firstName: "Marie", ... }, ... ] Expected Result: Returns an array of employees working on "Project Gamma". List employees who have more than 2 skills

Function Name: getEmployeesWithMoreThanTwoSkills Input: employees Output: [ { id: 1, firstName: "Jean", ... }, { id: 3, firstName: "Pierre", ... }, ... ] Expected Result: Returns an array of employees with more than 2 skills. Find employees whose last name starts with 'L'

Function Name: getEmployeesByLastNameInitial Input: employees, 'L' Output: [ { id: 5, lastName: "Leroux", ... }, { id: 8, lastName: "Laurent", ... }, ... ] Expected Result: Returns an array of employees whose last name starts with 'L'. Calculate the average salary per department

Function Name: calculateAverageSalaryByDepartment Input: employees Output: { "Développement": 60000, "Design": 50000, ... } Expected Result: Returns an object with average salaries for each department. Find employees who joined after 2020

Function Name: getEmployeesJoinedAfterYear Input: employees, 2020 Output: [ { id: 13, firstName: "Julie", ... }, { id: 18, firstName: "Romain", ... }, ... ] Expected Result: Returns an array of employees who joined after 2020. List employees who speak more than 2 languages

Function Name: getMultilingualEmployees Input: employees Output: [ { id: 3, firstName: "Pierre", ... }, { id: 5, firstName: "Camille", ... }, ... ] Expected Result: Returns an array of employees who speak more than 2 languages. Find the most common skill among all employees

Function Name: getMostCommonSkill Input: employees Output: "JavaScript" Expected Result: Returns the most common skill among all employees. List employees with a salary above 60000

Function Name: getHighEarningEmployees Input: employees, 60000 Output: [ { id: 3, firstName: "Pierre", ... }, { id: 8, firstName: "Nicolas", ... }, ... ] Expected Result: Returns an array of employees earning above 60000. Find the longest-serving employee

Function Name: getLongestServingEmployee Input: employees Output: { id: 34, firstName: "Paul", ... } Expected Result: Returns the employee who has been with the company the longest. Medium - Department Operations Count how many employees are in each department

Function Name: countEmployeesByDepartment Input: employees Output: { "Développement": 15, "Design": 10, "Marketing": 12, "Management": 13 } Expected Result: Returns an object with the count of employees in each department. Find the department with the most employees

Function Name: getLargestDepartment Input: employees Output: "Développement" Expected Result: Returns the name of the department with the most employees. Calculate the total salary expenditure per department

Function Name: calculateTotalSalaryByDepartment Input: employees Output: { "Développement": 750000, "Design": 450000, "Marketing": 600000, "Management": 800000 } Expected Result: Returns an object with the total salary expenditure for each department. List all positions in the "Marketing" department

Function Name: getPositionsInDepartment Input: employees, "Marketing" Output: ["Responsable SEO", "Chargée de communication", "Responsable marketing digital", ...] Expected Result: Returns an array of all unique positions in the "Marketing" department. Find the average number of projects per employee by department

Function Name: calculateAverageProjectsByDepartment Input: employees Output: { "Développement": 3.2, "Design": 2.5, "Marketing": 1.8, "Management": 2.7 } Expected Result: Returns an object with the average number of projects per employee for each department. Medium - Project Operations List all unique project names

Function Name: getUniqueProjectNames Input: employees Output: ["Project Alpha", "Project Beta", "Project Gamma", "Project Delta", "Project Epsilon"] Expected Result: Returns an array of all unique project names. Count how many employees work on each project

Function Name: countEmployeesByProject Input: employees Output: { "Project Alpha": 20, "Project Beta": 18, "Project Gamma": 15, "Project Delta": 12, "Project Epsilon": 10 } Expected Result: Returns an object with the count of employees working on each project. Find projects with only one employee assigned

Function Name: getSoloProjects Input: employees Output: ["Project Zeta"] Expected Result: Returns an array of project names with only one employee assigned. List employees who work on multiple projects

Function Name: getEmployeesWithMultipleProjects Input: employees Output: [ { id: 1, firstName: "Jean", ... }, { id: 3, firstName: "Pierre", ... }, ... ] Expected Result: Returns an array of employees who are assigned to multiple projects. Find the most popular project (most employees)

Function Name: getMostPopularProject Input: employees Output: "Project Alpha" Expected Result: Returns the name of the project with the most employees assigned. Advanced Advanced - Complex Data Transformations Create a new array with full names (firstName + lastName)

Function Name: getFullNames Input: employees Output: ["Jean Dupont", "Marie Martin", "Pierre Bernard", ...] Expected Result: Returns an array of full names for all employees. Normalize all names: capitalize first letter, lowercase rest

Function Name: normalizeNames Input: employees Output: ["Jean", "Marie", "Pierre", ...] Expected Result: Returns an array of normalized names. Create initials for each employee (e.g., "JD" for Jean Dupont)

Function Name: getEmployeeInitials Input: employees Output: ["JD", "MM", "PB", ...] Expected Result: Returns an array of initials for all employees. Add a new property 'yearsOfService' calculated from joinDate

Function Name: addYearsOfService Input: employees Output: [ { id: 1, yearsOfService: 6, ... }, { id: 2, yearsOfService: 5, ... }, ... ] Expected Result: Returns the employees array with an added 'yearsOfService' property. Create an object grouping employees by first letter of last name

Function Name: groupEmployeesByLastNameInitial Input: employees Output: { "D": [ { id: 1, ... }, { id: 10, ... } ], "M": [ { id: 2, ... }, { id: 9, ... } ], ... } Expected Result: Returns an object grouping employees by the first letter of their last name. Build a dictionary of projects with assigned employee names

Function Name: getProjectEmployeeDictionary Input: employees Output: { "Project Alpha": ["Jean Dupont", "Pierre Bernard", ...], "Project Beta": ["Marie Martin", ...], ... } Expected Result: Returns a dictionary of projects with the names of assigned employees. Create a nested structure: departments → projects → employees

Function Name: getDepartmentProjectEmployeeStructure Input: employees Output: { "Développement": { "Project Alpha": [ { id: 1, ... }, ... ], ... }, ... } Expected Result: Returns a nested structure grouping employees by department and project. Reverse all employee names (firstName and lastName separately)

Function Name: reverseEmployeeNames Input: employees Output: [ { id: 1, firstName: "naej", lastName: "tnopuD", ... }, ... ] Expected Result: Returns the employees array with reversed first and last names. Replace all vowels in names with '*'

Function Name: replaceVowelsInNames Input: employees Output: [ { id: 1, firstName: "J**n", lastName: "Dpnt", ... }, ... ] Expected Result: Returns the employees array with vowels in names replaced by '*'. Create a string of all employee emails separated by ';'

Function Name: getAllEmployeeEmails Input: employees Output: "jean.dupont@company.com;marie.martin@company.com;..." Expected Result: Returns a single string of all employee emails separated by ';'. Advanced - Statistical Analysis Calculate the median salary company-wide

Function Name: calculateMedianSalary Input: employees Output: 55000 Expected Result: Returns the median salary of all employees. Find the standard deviation of employee ages

Function Name: calculateAgeStandardDeviation Input: employees Output: 5.2 Expected Result: Returns the standard deviation of employee ages. Determine salary percentiles (25th, 50th, 75th)

Function Name: calculateSalaryPercentiles Input: employees Output: { "25th": 45000, "50th": 55000, "75th": 65000 } Expected Result: Returns an object with salary percentiles. Find the correlation between age and salary

Function Name: calculateAgeSalaryCorrelation Input: employees Output: 0.85 Expected Result: Returns the correlation coefficient between age and salary. Calculate the average number of skills by department

Function Name: calculateAverageSkillsByDepartment Input: employees Output: { "Développement": 4.2, "Design": 3.5, ... } Expected Result: Returns an object with the average number of skills per department. Find the most common language combination

Function Name: getMostCommonLanguageCombination Input: employees Output: ["French", "English"] Expected Result: Returns the most common combination of languages spoken by employees. Calculate the average project participation by age group

Function Name: calculateAverageProjectsByAgeGroup Input: employees Output: { "20-29": 2.5, "30-39": 3.2, "40-49": 3.8 } Expected Result: Returns an object with the average number of projects per age group. Determine the most frequent first name initial

Function Name: getMostFrequentFirstNameInitial Input: employees Output: "J" Expected Result: Returns the most frequent first name initial among employees. Find the average salary difference between active/inactive employees

Function Name: calculateSalaryDifferenceByStatus Input: employees Output: { "active": 58000, "inactive": 52000, "difference": 6000 } Expected Result: Returns an object with the average salary difference between active and inactive employees. Calculate the retention rate by join year

Function Name: calculateRetentionRateByYear Input: employees Output: { "2019": 0.85, "2020": 0.90, ... } Expected Result: Returns an object with retention rates by join year. Advanced - Search and Grouping Find employees whose skills include both "JavaScript" and "React"

Function Name: findEmployeesWithSpecificSkills Input: employees, ["JavaScript", "React"] Output: [ { id: 1, firstName: "Jean", ... }, { id: 13, firstName: "Julie", ... } ] Expected Result: Returns an array of employees whose skills include both "JavaScript" and "React". List employees with special characters in their last names

Function Name: findEmployeesWithSpecialCharacters Input: employees Output: [ { id: 35, lastName: "Rivière", ... }, { id: 46, lastName: "Martínez", ... } ] Expected Result: Returns an array of employees whose last names contain special characters. Find employees whose email domain is not "company.com"

Function Name: findEmployeesWithDifferentEmailDomain Input: employees Output: [] Expected Result: Returns an array of employees whose email domain is not "company.com". Group employees by number of projects (0, 1-2, 3+)

Function Name: groupEmployeesByProjectCount Input: employees Output: { "0": [ { id: 12, ... }, { id: 24, ... } ], "1-2": [ { id: 9, ... }, { id: 13, ... } ], "3+": [ { id: 8, ... }, { id: 34, ... } ] } Expected Result: Returns an object grouping employees by the number of projects they are assigned to. Find employees with anagrams in their names (e.g., "Jean" and "Jane")

Function Name: findEmployeesWithAnagramNames Input: employees Output: [ { id: 1, firstName: "Jean", ... }, { id: 13, firstName: "Jane", ... } ] Expected Result: Returns an array of employees whose names are anagrams of each other. List employees whose full name contains all vowels

Function Name: findEmployeesWithAllVowelsInName Input: employees Output: [ { id: 17, firstName: "Amandine", lastName: "Perrot", ... } ] Expected Result: Returns an array of employees whose full names contain all vowels (a, e, i, o, u). Find employees with the same first name but different last names

Function Name: findEmployeesWithSameFirstName Input: employees Output: { "Hugo": [ { id: 8, lastName: "Laurent", ... }, { id: 48, lastName: "Martinez", ... } ] } Expected Result: Returns an object grouping employees with the same first name but different last names. Group employees by the length of their first name

Function Name: groupEmployeesByFirstNameLength Input: employees Output: { "3": [ { id: 8, firstName: "Hugo", ... } ], "4": [ { id: 1, firstName: "Jean", ... }, { id: 2, firstName: "Marie", ... } ], ... } Expected Result: Returns an object grouping employees by the length of their first name. Find employees whose last name is a palindrome

Function Name: findEmployeesWithPalindromeLastName Input: employees Output: [ { id: 11, lastName: "Lefevre", ... } ] Expected Result: Returns an array of employees whose last names are palindromes. Create a search function that finds employees by any property value

Function Name: searchEmployeesByProperty Input: employees, "department", "Développement" Output: [ { id: 1, ... }, { id: 4, ... }, { id: 6, ... } ] Expected Result: Returns an array of employees matching the specified property value. Bonus Challenges Create a function to validate employee data (check for required fields) Build a nested object showing employees grouped by department then project Simulate a search system that finds employees matching multiple criteria Create a promotion eligibility checker based on years of service and performance Build a team generator that creates balanced teams based on skills Notes Focus on using only loops and conditions Avoid using advanced array methods unless explicitly required The employee data structure should remain unchanged Try to optimize your code for readability and clarity