flot jquery动态数据问题

[wcf2010]

<%//我的是java 想做一个动态刷新效果 请看这里http://people.iola.dk/olau/flot/examples/ajax.html
String data1="data:[[0,0],[5,5],[6,10],[7,8],[10,20],[11,21],[12,22],[13,23],[14,24],[15,25],[16,16],[17,27],[18,28],[19,5],[20,20],[21,18],[23,15],[25,16],[26,5],[28,15]]";
//[[1999, 3.0], [2000, 3.9], [2001, 2.0], [2002, 1.2], [2003, 1.3], [2004, 2.5], [2005, 2.0], [2006, 3.1], [2007, 2.9], [2008, 0.9]]

String pv1="[{"+la+","+data1+"}]";
%>
<script>
$(function () {
var data = <%=pv1%> ;
var options = {
series: {
lines: { show: true },

points: { show: true }
},
grid:{labelMargin:1},
legend: { noColumns: 2 },
xaxis: { tickDecimals: 0,min:0,max:30, tickDecimals: 0,ticks:50, tickSize: 3,minTickSize:0.01,tickFormatter:100 },
yaxis: { min: 0 ,max:30},
selection: { mode: "x" }
};



$("#placeholder").bind("plotselected", function (event, ranges) {

$.plot( $("#placeholder"), data,
$.extend(true, {}, options, {
xaxis: { min: ranges.xaxis.from, max: ranges.xaxis.to }
}));
});


$.plot( $("#placeholder"), data, options);

//更新数据
$("input.dataUpdate").click(function () {

mydata = [];
$.plot($("#placeholder"), mydata, options);

var iteration = 0;//重复次数
//取得数据
function fetchData() {
++iteration;
//数据被取得
function onDataReceived(data) {

mydata = data;

$.plot($("#placeholder"), mydata, options);
}
//刷新
$.ajax({
success: onDataReceived
});

if (iteration < 5)
//周期性执行函数fetchData()
setTimeout(fetchData, 1000);
else {
mydata = [];
}
}
//周期性执行函数fetchData()
setTimeout(fetchData, 1000);
});
});
<script>