• Write a function for creating persons.
  • Each person must have firstname, lastname, age and gender (true is female, false is male)
• Generate an array with ten person with different names, ages and genders

• Write a function that checks if an array of person contains only people of age (with age 18 or greater)
  • Use only array methods and no regular loops (for, while)

• Write a function that prints all underaged persons of an array of person
  • Use Array#filter and Array#forEach
  • Use only array methods and no regular loops (for, while)

• Write a function that calculates the average age of all females, extracted from an array of persons
  • Use Array#filter
  • Use only array methods and no regular loops (for, while)

• Write a function that finds the youngest male person in a given array of people and prints his full name
  • Use only array methods and no regular loops (for, while)
  • Use Array#find

• Write a function that groups an array of persons by first letter of first name and returns the groups as a JavaScript Object
  • Use Array#reduce
  • Use only array methods and no regular loops (for, while)

Example:

    result = {
        'a': [{
            firstname: 'Asen',
            /* ... */
        }, {
            firstname: 'Anakonda',
            /* ... */
        }],
        'j': [{
            firstname: 'John',
            /* ... */
        }]
    };