kata solution

list.js

function list(names){

  const arrayLen = names.length
  
  return names.reduce((previousValue, currentValue, currentIndex)=>{
   
    if(currentIndex === arrayLen-1)
      return previousValue+currentValue.name

    if(currentIndex === arrayLen-2)
      return previousValue+currentValue.name+' & '

    
    return previousValue+currentValue.name+','+' '
  },'')

}


function list(names) {
  var xs = names.map(p => p.name)
  var x = xs.pop()
  return xs.length ? xs.join(", ") + " & " + x : x || ""
}


var list = (names) =>  names.map(x => x.name).join(', ').replace(/(.*),(.*)$/, "$1 &$2")


function list(names) {
  return names.map(o => o.name).join(', ').replace(/^(.*)(, )(.*)$/, '$1 & $3');
}

function list(names){
  return names
           .map((item) => item.name)
           .join(', ')
           .replace(/,\s([^,]+)$/, ' & $1');
}

function list(names){
  var last = names.pop() || { name: '' }
  result = names.map(function(n) { return n.name }).join(', ')
  return result ? result + ' & ' + last.name : last.name
}

function list(names){
  names = names.map(function(v){return v.name});
  return names.concat(names.splice(-2).join(' & ')).join(', ');
}