6-14_JS.js

// //  PROBLEM #1 //
// // You will be given an array of objects (associative arrays in PHP) representing data about developers
// // who have signed up to attend the next coding meetup that you are organising.
// // Your task is to return an object (associative array in PHP) which includes
// // the count of each coding language represented at the meetup.
// // For example, given the following input array:
// var count = {};
// var list1 = [
//   { firstName: 'Noah', lastName: 'M.', country: 'Switzerland', continent: 'Europe', age: 19, language: 'C' },
//   { firstName: 'Anna', lastName: 'R.', country: 'Liechtenstein', continent: 'Europe', age: 52, language: 'JavaScript' },
//   { firstName: 'Ramon', lastName: 'R.', country: 'Paraguay', continent: 'Americas', age: 29, language: 'Ruby' },
//   { firstName: 'George', lastName: 'B.', country: 'England', continent: 'Europe', age: 81, language: 'C' },
// ];
// // your function should return the following object (associative array in PHP):
// // { C: 2, JavaScript: 1, Ruby: 1 }
// // */

// const lang= list1.map(x => x.language) //this = [C, Javascript, Ruby]


//  lang.forEach(function(i) {count[i] = (count[i]||0)+1;  });

//  console.log(count);


//  another example:


// uniqueCount = ['a','b','c','d','d','e','a','b','c','f','g','h','h','h','e','a'];
// var new_array = new Object();

// for(var i = 0; i < uniqueCount.length; i++) {
//  if(new_array[uniqueCount[i]] != null) {
//     new_array[uniqueCount[i]] += 1;
// } else {
//     new_array[uniqueCount[i]] = 1;
//     }
// }
// console.log(map);

// ----------------------------------


                                              // PROBLEM #2 //
// You will be given an array of objects representing data about developers who have signed up to attend
// the next coding meetup that you are organising.
// Given the following input array:
// var list1 = [
//   { firstName: 'Maria', lastName: 'Y.', country: 'Cyprus', continent: 'Europe', age: 30, language: 'Java' },
//   { firstName: 'Victoria', lastName: 'T.', country: 'Puerto Rico', continent: 'Americas', age: 70, language: 'Python' },
// ];


// // write a function that returns the average age of developers (rounded to the nearest integer). 
// //   In the example above your function should return 50 (number).
// //   Notes:
// //   The input array will always be valid and formatted as in the example above.
// //   Age is represented by a number which can be any positive integer. 

// var sum = 0;
// const dev_age= list1.map(x => x.age)

// for (var i=0; i < dev_age.length; i++) {
//   sum = dev_age[i] + sum

// }
// var total = sum / dev_age.length
// console.log(total);


// --------------------------------
//        // PROBLEM #3 //
// Given the following input array:
// var list1 = [
//   { firstName: 'Emily', lastName: 'N.', country: 'Ireland', continent: 'Europe', age: 30, language: 'Ruby' },
//   { firstName: 'Nor', lastName: 'E.', country: 'Malaysia', continent: 'Asia', age: 20, language: 'Clojure' }
// ];
// // write a function that adds the username property to each object in the input array:
// // [
// //   // { firstName: 'Emily', lastName: 'N.', country: 'Ireland', continent: 'Europe', age: 30, language: 'Ruby', 
//   //   username: 'emilyn1990' },
//   // { firstName: 'Nor', lastName: 'E.', country: 'Malaysia', continent: 'Asia', age: 20, language: 'Clojure', 
//   //   username: 'nore2000' }
// // ]
// //   The value of the username property is composed by concatenating:
// //   firstName in lower-case;
// //   first letter of the lastName in lower-case; and
// //   the birth year which for the purpose of this kata is calculated simply by subtracting age from the current year. 
// //   Please make sure that your function delivers the correct birth year irrespective of when it will be executed, 
// //   for example it should also work correctly for a meetup organised in 10-years-time. 
// //   The example above assumes that the function is run in year 2020.
// //   Notes:
// //   The input array will always be valid and formatted as in the example above.
// //   Age is represented by a number which can be any positive integer.
// //   Lastname will always be one upper-cased letter followed by dot, e.g. 'N.'
// //   Order of the objects in the array should be maintained but order of the properties in the individual objects does not matter. 
// // */
// var year = new Date().getFullYear()
// const user = list1.map(x => x.firstName.toLowerCase() + x.lastName.toLowerCase() + (year - x.age))

// console.log(user);






                                              // PROBLEM #4 //
  // You have an array of numbers.
  // Your task is to sort ascending even numbers but odd numbers must be on their places.
  // Zero isn't an odd number and you don't need to move it. If you have an empty array, you need to return it.
  // // Example
  // arr = [5, 3, 2, 8, 1, 4]
  // // Trick is to create an array of the odd numbers using filter, then map them back into the starting array:
 
  // function sortArray(arr) {
  //           const even = arr.filter((x) => x % 2 == 0).sort((a,b) => a - b);
  //          return arr.map((x) => x % 2== 0 ? even.shift() : x);
  //         }
  // console.log(sortArray(arr));