.td_back_color { 
  background-color: red; 
} 
.td_center { 
  text-align: center; 
  font-weight:bold; 
} 

<table id="tbl_count"> 
      <caption>2013春节聚会收支统计</caption> 
      <tr> 
        <th>姓名</th> 
        <th>吃饭</th> 
        <th>KTV</th> 
        <th>烧烤</th> 
        <th>支出</th> 
        <th>应付</th> 
      </tr> 
      <tr> 
        <th>周竞成</th> 
        <td></td> 
        <td></td> 
        <td></td> 
        <td></td> 
        <td></td> 
      </tr> 
      ...... 
    </table> 

var data = [ { 
      picture : "http://ww1.sinaimg.cn/mw690/51baa38egw1dzl6l2hjchj.jpg", 
      name : "周竞成", 
      leftTime : "二月五号", 
      phone : "186****2296", 
      qq : "", 
      workedIn : "浙江 杭州", 
      cost : 200, 
      project : "吃饭，KTV，烧烤" 
    }, ........ 


// 初始化shuju 
    var init = function() { 
      var tbl_count = $("#tbl_count tr:gt(0)"); 
      // 吃饭 
      var meal_text = $("#tbl_count tr:first th:eq(1)").text(); 
      // KTV 
      var ktv_text = $("#tbl_count tr:first th:eq(2)").text(); 
      // 烧烤 
      var bbq_text = $("#tbl_count tr:first th:eq(3)").text(); 
 
      $.each(tbl_count, function(i,v){ 
        var tr_info = tbl_count.eq(i); 
        for (var i = 0; i < data.length; i++) { 
          var data_info = data[i]; 
          // 判断姓名相同的 
          if(data_info.name == tr_info.find("th:first").text()){ 
            if(data_info.project.indexOf(meal_text) != -1){ 
              tr_info.find("td:eq(0)").addClass("td_back_color"); 
            } 
            if(data_info.project.indexOf(ktv_text) != -1){ 
              tr_info.find("td:eq(1)").addClass("td_back_color"); 
            } 
            if(data_info.project.indexOf(bbq_text) != -1){ 
              tr_info.find("td:eq(2)").addClass("td_back_color"); 
            } 
            tr_info.find("td:eq(3)").addClass("td_center").text("￥"+data_info.cost); 
          } 
        } 
      }); 
    }; 

var rowCount = $('#myTable tr').length; 

var rowCount = $('#myTable >tbody >tr').length; 

$("#myTable").attr('rows').length; 

var rowCount = $('table#myTable:last').index() + 1; 

//Helper function that gets a count of all the rows <TR> in a table body <TBODY> 
$.fn.rowCount = function() { 
  return $('tr', $(this).find('tbody')).length; 
}; 
 
// USAGE: 
 
var rowCount = $('#productTypesTable').rowCount(); 

alert(jQuery("#jtkList").find("table").eq(0).find("tr").length);