function Pager(tableName, itemsPerPage) {
    this.tableName = tableName;
    this.itemsPerPage = itemsPerPage;
    this.currentPage = 1;
    this.pages = 0;
    this.inited = false;

    this.showRecords = function(from, to) {        
        var rows = document.getElementById(tableName).rows;
		var bg = 'odd';

        // i starts from 1 to skip table header row
        for (var i = 1; i < rows.length; i++) {
            if (i < from || i > to)  {
                rows[i].style.display = 'none';
            }
            else {
				bg = ( bg == 'odd' ) ? 'even' : 'odd';
            	rows[i].style.display = '';
            	if ( bg == 'odd' ) {
                	rows[i].style.background = '#e8f4ff';
            	}
            }
        }
    }
    
    this.showPage = function(pageNumber) {
    	if (! this.inited) {
    		alert("not inited");
    		return;
    	}

        var oldPageAnchor = document.getElementById('pg_'+this.tableName+this.currentPage);
        if(oldPageAnchor) {
        	oldPageAnchor.className = 'nav_link_normal';
        }
        
        this.currentPage = pageNumber;
        var newPageAnchor = document.getElementById('pg_'+this.tableName+this.currentPage);
        if (newPageAnchor) {
        	newPageAnchor.className = 'nav_link_active';
        }
        
        var from = (pageNumber - 1) * itemsPerPage + 1;
        var to = from + itemsPerPage - 1;
        this.showRecords(from, to);
    }              
    
    this.init = function() {
        var rows = document.getElementById(tableName).rows;
        var records = (rows.length - 1); 
        this.pages = Math.ceil(records / itemsPerPage);
        this.inited = true;
    }

    this.showPageNav = function(pagerName, positionId) {
    	if (! this.inited) {
    		alert("not inited");
    		return;
    	}

    	var element = document.getElementById(positionId);
    	
    	var pagerHtml = '';
        for (var page = 1; page <= this.pages; page++) {
            pagerHtml += '<div id="pg_' + this.tableName + page + '" class="nav_link_normal"><a  class="" onclick="' + pagerName + '.showPage(' + page + ');">' + page + '</a></div>';
			if ( page < this.pages ) {           
				//pagerHtml += '<span class="vertical_bar">| </span>';
			}
        }
        if (this.pages == 1) {
        	pagerHtml = '<div id="pg_' + this.tableName + 1 + '" class="nav_link_active" onclick="' + pagerName + '.showPage(' + 1 + ');"></div> ';
        }
        
        element.innerHTML = pagerHtml;
    }
}