paginations class js setup

pagination-class.js

// TODO: complete this object/class

// The constructor takes in an array of items and a integer indicating how many
// items fit within a single page
function PaginationHelper(collection, itemsPerPage) {
	this.collection = collection;
	this.itemsPerPage = itemsPerPage;
	
}

// returns the number of items within the entire collection
PaginationHelper.prototype.itemCount = function() {
	return this.collection.length;
}

// returns the number of pages
PaginationHelper.prototype.pageCount = function() {
	return Math.ceil(this.itemCount() / this.itemsPerPage);
}

// returns the number of items on the current page. page_index is zero based.
// this method should return -1 for pageIndex values that are out of range
PaginationHelper.prototype.pageItemCount = function(pageIndex) {
	if(pageIndex < 0 || pageIndex > this.pageCount()) {
		return -1;
	}

	return Math.ceil(pageIndex + 1)* this.itemsPerPage;
}

// determines what page an item is on. Zero based indexes
// this method should return -1 for itemIndex values that are out of range
PaginationHelper.prototype.pageIndex = function(itemIndex) {
	if(itemIndex < 0 || itemIndex > this.itemCount()) {
		return -1;
	}
	return 'not the right answer';
}