simple swap in javascript

simple swap

function reverse(str)
{
    console.log('INPUT ARRAY ' + str.join(''))

    var r = str.length - 1, l = 0;
    while (l < r)
    {
      swap(l, r);
      l++;
      r--;
    }
  
  function swap(from , to){
    var temp =  str[from];
    str[from] = str[to];
    str[to] = temp;
  }
  
  console.log('OUTPUT ARRAY ' + str.join(''))
}

var string = 'abcdefgh'
reverse(string.split(''))