Javascript - How to add string at the end of cycle

Seona16
October 3, 2023
223 views
2 votes
4 Answers

I have the array and need to divide 3 student per 3 array. Need to get the following results per cases:

sortStudentsByGroups(students) =>

[  [ 'Andrew', 'Ann', 'Bernard' ],  [ 'Cris', 'Josh', 'Mark' ],  [ 'Peter', 'Sam', 'Sandra' ],  'Rest students: Takesi']

if to delete one student from the list, will get:

[
  [ 'Andrew', 'Ann', 'Bernard' ],
  [ 'Cris', 'Josh', 'Mark' ],
  [ 'Peter', 'Sam', 'Sandra' ],
  'Rest students: -'
]

My CODE:

const students = [
  "Peter",
  "Andrew",
  "Ann",
  "Mark",
  "Josh",
  "Sandra",
  "Cris",
  "Bernard",
  "Takesi",
  "Sandra",
];

function sortStudentsByGroups(arr) {
  arr.sort();
  const arrNew = [];
  const arr_size = 3;

  for (let i = 0; i < arr.length; i += arr_size) {
    let y = arr.slice(i, i + arr_size);

    arrNew.push(y);

    if (y.length < 3) {
      let u = y.join(", ");
      arrNew.push(`Rest students: ${u}`);
    }
  }

  console.log(arrNew);
}

sortStudentsByGroups(students);

For 1 option I have correct result:

[
  [ 'Andrew', 'Ann', 'Bernard' ],
  [ 'Cris', 'Josh', 'Mark' ],
  [ 'Peter', 'Sandra', 'Sandra' ],
  [ 'Takesi' ],
  'Rest students: Takesi'
]

And don’t know how to get result for 2-nd option, exactly add to arr ‘Rest students: -‘

[
  [ 'Andrew', 'Ann', 'Bernard' ],
  [ 'Cris', 'Josh', 'Mark' ],
  [ 'Peter', 'Sam', 'Sandra' ],
  'Rest students: -'
]

I tried to push in array and as the result iterating every time

Tags: javascript

Answers

One possibility would be to distribute normally, then pick the last element and check its size:

function sortStudentsByGroups(arr, size) {
    const arrNew = [];

    for (let i = 0; i < arr.length; i += size) 
        arrNew.push(arr.slice(i, i + size))
    
    let last = arrNew.pop()

    if (last.length < size)
        arrNew.push('Rest: ' + last.join())
    else
        arrNew.push(last, 'Rest: -')

    return arrNew
}

console.log(...sortStudentsByGroups('A B C D E F'.split(' '), 3))
console.log(...sortStudentsByGroups('A B C D E F G'.split(' '), 3))
console.log(...sortStudentsByGroups('A B C D E F G H'.split(' '), 3))

you can do your function like that:

function sortStudentsByGroups(arr) {
  arr.sort();
  const arrNew = [];
  const arr_size = 3;

  let remainingStudents = [...arr];

  for (let i = 0; i < arr.length; i += arr_size) {
    let y = remainingStudents.slice(0, arr_size);

    arrNew.push(y);

    if (y.length < 3) {
      let u = y.join(", ");
      arrNew.push(`Rest students: -`);
    }

    remainingStudents = remainingStudents.slice(arr_size);
  }

  console.log(arrNew);
}

You have handled the case, when you have "y" value <3 i.e, if y is 3, then you have appended right? so if the no. of people are multiple of 3 only, your 2nd test case fails.

so, you can add else condition here,

const students = [
  "Peter",
  "Andrew",
  "Ann",
  "Mark",
  "Josh",
  "Sandra",
  "Cris",
  "Bernard",
  "Takesi",
  "Sandra",
];

function sortStudentsByGroups(arr) {
  arr.sort();
  const arrNew = [];
  const arr_size = 3;

  for (let i = 0; i < arr.length; i += arr_size) {
    let y = arr.slice(i, i + arr_size);

    arrNew.push(y);

    if (y.length < 3) {
      let u = y.join(", ");
      arrNew.push(`Rest students: ${u}`);
    }
    if (i+arr_size >= arr.length){
    arrNew.push("Rest students: -");
    }
    

  }

  console.log(arrNew);
}

Move your rest students logic outside the loop and use

arr.slice(-arr.length % arr_size || arr.length)

to get the remaining students and join them with , .
If the string is empty that means no students left, so add || '-' to display the dash.

Btw you mutate the original array with sort(). If that’s not desired, just copy the array: arr = arr.slice().sort().

const students = [
  "Peter",
  "Andrew",
  "Ann",
  "Mark",
  "Josh",
  "Sandra",
  "Cris",
  "Bernard",
  "Takesi",
  "Sandra",
];

const students2 = [
  "Peter",
  "Andrew",
  "Ann",
  "Mark",
  "Josh",
  "Sandra",
  "Cris",
  "Bernard",
  "Sandra",
];

function sortStudentsByGroups(arr) {
  arr.sort();
  const arrNew = [];
  const arr_size = 3;

  for (let i = 0; i < arr.length; i += arr_size) {
    let y = arr.slice(i, i + arr_size);
    arrNew.push(y);
  }
  
  arrNew.push(`Rest students: ${arr.slice(-arr.length % arr_size || arr.length).join(', ') || '-'}`);

  return arrNew;
}

sortStudentsByGroups(students).map(item => console.log(JSON.stringify(item)));
sortStudentsByGroups(students2).map(item => console.log(JSON.stringify(item)));

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Javascript – How to add string at the end of cycle

Answers