Showing X to Y of Z Products. Given the page number, page size, and the total number of product.

XtoYofZ.js

//my solution
var paginationText = function(pageNumber, pageSize, totalProducts){
  var numOfPages = Math.ceil(totalProducts/pageSize);
  var initItem = pageNumber*pageSize-(pageSize-1);
  var endItem;
  if (pageNumber === numOfPages){
    endItem = totalProducts;
  }else{
    endItem = pageSize*pageNumber;
  };
  return "Showing " + initItem + " to " + endItem + " of " + totalProducts + " Products.";
}

//good examples
//1
var paginationText = function(pageNumber, pageSize, totalProducts){
  return 'Showing ' + (((pageNumber - 1) * pageSize) + 1) + ' to ' + Math.min(pageSize * pageNumber, totalProducts) + ' of ' + totalProducts + ' Products.';
}

//2
var paginationText = function(p, sz, total) {
  return 'Showing ' + ((p - 1) * sz + 1) + " to " + (p * sz > total ? total : p * sz) +
         " of " + total + " Products.";
}