uncaught typeerror undefined is not a function flotjs

Question

I have been trying to plot graphics in real time with flotjs.The external data is coming from arduino.My problem is getting this error:uncaught typeerror undefined is not a function

var socket = io.connect('http://localhost:8000');

      socket.on('pulse', function(data){
       
          var datas = [],
          totalPoints = 300;

        function getData() {

          if (datas.length > 0)
            datas = datas.slice(1);

          // Do a random walk

          while (datas.length < totalPoints) {

            datas.push(data);
          }

          // Zip the generated y values with the x values

          var res = [];
          for (var i = 0; i < datas.length; ++i) {
            res.push([i, datas[i]]);
          }

          return res;
        }

        var plot = $.plot("#placeholder", [ getData() ], {
          series: {
            shadowSize: 0 // Drawing is faster without shadows
          },
          yaxis: {
            min: 0,
            max: 100
          },
          xaxis: {
            show: false
          }
        });

        function update() {

          plot.setData([getData()]);

          // Since the axes don't change, we don't need to call plot.setupGrid()

          plot.draw();
          setTimeout(update, updateInterval);
        }

        update();

the error has occured this line:
var plot = $.plot("#placeholder", [ getData() ], { ...

what is the problem?

Answer 1

I solved.It had not been just serving static files.