Infinite Array Pagination

infiniteArrayPagination.js

/**
* Takes an array, a given window size and 
* a starting index and returns a fragment of the
* array with infinite pagination.
* If the window size if bigger than teh array size,
* it shouldn't be paginated.
**/

const a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];

function infinitePagination(index, size, array) {
  // Limit index to availables in length.
  const i = index % array.length;
  // Limit size to avoid showing duplicated items.
  const l = Math.min(size - 1, array.length -1);
  const c = array.length - l;
  const frag1 = array.slice(array.length + i - 1, array.length);
  const frag2 = array.slice(i - 1, i);
  const frag3 = array.slice(i, i + l);
  const frag4 = array.slice(0, Math.max(0, i - c));

  return [...frag1, ...frag2, ...frag3, ...frag4];
}

const width = 7;

console.log(infinitePagination(0, width, a));  // [11, 0, 1, 2, 3, 4, 5]   
console.log(infinitePagination(1, width, a));  // [0, 1, 2, 3, 4, 5, 6]    
console.log(infinitePagination(2, width, a));  // [1, 2, 3, 4, 5, 6, 7]    
console.log(infinitePagination(3, width, a));  // [2, 3, 4, 5, 6, 7, 8]    
console.log(infinitePagination(4, width, a));  // [3, 4, 5, 6, 7, 8, 9]    
console.log(infinitePagination(5, width, a));  // [4, 5, 6, 7, 8, 9, 10]   
console.log(infinitePagination(6, width, a));  // [5, 6, 7, 8, 9, 10, 11]  
console.log(infinitePagination(7, width, a));  // [6, 7, 8, 9, 10, 11, 0]  
console.log(infinitePagination(8, width, a));  // [7, 8, 9, 10, 11, 0, 1]  
console.log(infinitePagination(9, width, a));  // [8, 9, 10, 11, 0, 1, 2]  
console.log(infinitePagination(10, width, a)); // [9, 10, 11, 0, 1, 2, 3]  
console.log(infinitePagination(11, width, a)); // [10, 11, 0, 1, 2, 3, 4]  
console.log(infinitePagination(12, width, a)); // [11, 0, 1, 2, 3, 4, 5]   
console.log(infinitePagination(13, width, a)); // [0, 1, 2, 3, 4, 5, 6]    
console.log(infinitePagination(14, width, a)); // [1, 2, 3, 4, 5, 6, 7]    
console.log(infinitePagination(15, width, a)); // [2, 3, 4, 5, 6, 7, 8]    
console.log(infinitePagination(16, width, a)); // [3, 4, 5, 6, 7, 8, 9]    
console.log(infinitePagination(17, width, a)); // [4, 5, 6, 7, 8, 9, 10]   
console.log(infinitePagination(18, width, a)); // [5, 6, 7, 8, 9, 10, 11]  
console.log(infinitePagination(19, width, a)); // [6, 7, 8, 9, 10, 11, 0]  
console.log(infinitePagination(20, width, a)); // [7, 8, 9, 10, 11, 0, 1]