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 rows = tableName.rows;
    // 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
            rows[i].style.display = '';
    }
}

this.showPage = function(pageNumber) {
    if (! this.inited) {
        alert("not inited");
        return;
    }

    var oldPageAnchor = document.getElementById('pg'+this.currentPage);
    oldPageAnchor.className = 'pg-normal';
    
    this.currentPage = pageNumber;
    var newPageAnchor = document.getElementById('pg'+this.currentPage);
    newPageAnchor.className = 'pg-selected';
    
    var from = (pageNumber - 1) * itemsPerPage + 1;
    var to = from + itemsPerPage - 1;
    this.showRecords(from, to);
}   

this.prev = function() {
    if (this.currentPage > 1)
        this.showPage(this.currentPage - 1);
}

this.next = function() {
    if (this.currentPage < this.pages) {
        this.showPage(this.currentPage + 1);
    }
}                        

this.init = function() {
    
    //var rows = document.getElementById(tableName).rows;
    var rows = tableName.rows;
    
    var records = (rows.length - 1); 
    this.pages = Math.ceil(records / itemsPerPage);
    this.inited = true;
    
}

this.showPageNav = function(pagerName, positionId, sqlPageNumber) {
    if (! this.inited) {
        alert("not inited");
        return;
    }
    var element = document.getElementById(positionId);
	
    var pagerHtml = '<span onclick="' + pagerName + '.prev();" class="pg-normal"> &#171 Anterior </span> | ';
    for (var page = 1; page <= this.pages; page++) 
        pagerHtml += '<span id="pg' + page + '" class="pg-normal" onclick="' + pagerName + '.showPage(' + page + ');">' + (page + (sqlPageNumber * 5)) + '</span> | ';
    pagerHtml += '<span onclick="'+pagerName+'.next();" class="pg-normal"> Siguiente &#187;</span>';            
    
    element.innerHTML = pagerHtml;
}
}