shuffle and group

studentShuffle.js

function shuffleAndGroup (students, sizeGroups = 2) {

  var shuffled = students.reduce( (acc, item, i, array) => {
    var random = Math.floor(Math.random() * array.length);
    array[i] = array.splice(random,1,item)[0]
    return array
  },[])

  var grouped = shuffled.reduce((acc, current, index, array) => {
    if (index % sizeGroups) {
      acc[acc.length - 1].push(current) // add elements to the group
    } else {
      acc.push([current]) // new group
    }
    return acc
  }, [])

  return grouped // return an array of arrays (pairs)
}

var students = ['Emilio', 'Jose Manuel', 'Abel', 'Jese', 'Oscar', 'Nacho', 'Pol', 'Joan Marc', 'Francesc', 'Toni', 'Eva', 'Gemma']

shuffleAndGroup(students, 2)
  .forEach((group, i) => {
    console.log('----------------')
    console.log(`GROUP ${i + 1}`)
    group.forEach(student => console.log(student))
  })