Algorithm for finding shortest page for fetching results, given low and high index

getPage.js

/*  
 *  Find smallest page and per_page limit to retrieve a range of results, given low and high  
 *  For non-offset pased paging APIs (where one must send 'per_page' and 'page', rather than offset and limit)
 *
 *  params:
 *    (integer) low:  lowest index to fetch (zero-based)
 *    (integer) high:  highest index to fetch (zero-based)
 *
 *  return value:
 *     [(integer) per_page, (integer) page]
 *
 *  Example:  get page for items 33-39
 *    getPage(33,39) =>  [8, 5]
 *    Fetch page 5, with per_page setting of 8 (will receive indices 32-39)
 */
function getPage(low, high) {
  var range = high - low + 1; 
  if (range < low) {
    for (var perpage = range; perpage <= low; perpage++ ) {
      if (low % perpage <= perpage - range) {
        var offset = Math.floor(low / perpage);
        return [perpage, offset + 1];
      }
    }
  } else {
    return [high + 1, 1];
  }
}