root/trunk/paginateddatasource.js

// Make a datasource paginatable
// The data must be in array form

// All you have to do is include this library. Then if you want to convert a datasource to be
// paginated, simply call myDataSource.makePaginated().
DataSource.prototype.extend({
  makePaginated: function (opts) {
      if (opts)
          this.dataField = opts.dataField;

    this.extend({

  // returns how many pages there are
  getPageCount: function () {
    return Math.ceil(this.totalLength() / this.getItemsPerPage()) || 1;
  },

  // returns what page we're on
  getCurrentPage: function () {
    return this.currentPage;
  },

  // returns how many items are on a page
  getItemsPerPage: function () {
    return this.itemsPerPage;
  },

                  // set items per page
                  setItemsPerPage: function (itemCount) {
                    if (itemCount > 0)
                      this.itemsPerPage = itemCount;

                    this._updated();
                  },

                  // set the current page
                  setCurrentPage: function (page) {
                    if (page > this.getPageCount() - 1)
                      page = this.getPageCount() - 1;

                    if (page < 0)
                      page = 0;

                    this.currentPage = page;

                    this._updated();
                  },

                  // go to the next page
                  goNextPage: function () {
                    this.setCurrentPage(this.getCurrentPage() + 1);

                    this._updated();
                  },

                  // go to the previous page
                  goPrevPage: function () {
                    this.setCurrentPage(this.getCurrentPage() - 1);

                    this._updated();
                  }

                  });

    // overloaded data accessor that returns data for the current page
  this.data = function () {
    var theData = this.theData;

    if (this.dataField && theData) {
        theData = theData[this.dataField];
    }

    if (!theData || !theData.length)
      return [];

    var startIndex = this.getCurrentPage() * this.getItemsPerPage();
    var endIndex = theData.fitIndex(startIndex + this.getItemsPerPage());

    // slice the array
    var newData = [];
    var j=0;
    for (var i = startIndex; i <= endIndex; i++)
      newData[j++] = theData[i];

    return newData;
  };

  // return all the data, not just the current page's
  this.allData = function () {
    return this.theData;
  };

  this.isPaginated = true;
  this.itemsPerPage = 7;
  this.currentPage = 0;
  }});