d3

  createVisitsTimeSeries: function(container, visit_data){
    var margin = {top: 5, right: 5, bottom: 5, left: 5},
    width = $(container).width() - (margin.left - margin.right),
    height = $(container).height() + 50;

    var parseDate = d3.time.format("%Y-%m-%d").parse;

    entries = d3.values(visit_data);

    var x = d3.time.scale()
        .range([0, width]);

    var y = d3.scale.linear()
        .range([height, 0]);

    var xAxis = d3.svg.axis()
        .scale(x)
        .orient("bottom");

    var yAxis = d3.svg.axis()
        .scale(y)
        .orient("left");

    var area = d3.svg.area()
        .x(function(d) { return x(d.date); })
        .y0(height)
        .y1(function(d) { return y(d.visits); });

    var svg = d3.select(container).append("svg")
        .attr("width", width + margin.left + margin.right)
        .attr("height", height + margin.top + margin.bottom)
      .append("g")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
        console.log('visits', visit_data);

      x.domain(d3.extent(entries, function(d) {
        console.log('d', d);
        return d.date; }));
      y.domain([0, d3.max(entries, function(d) { return d.visits; })]);

      svg.append("path")
          .datum(entries)
          .attr("class", "area")
          .attr("d", area);

      svg.append("g")
          .attr("class", "x axis")
          .attr("transform", "translate(0," + height + ")")
          .call(xAxis);

      svg.append("g")
          .attr("class", "y axis")
          .call(yAxis)
        .append("text")
          .attr("transform", "rotate(-90)")
          .attr("y", 6)
          .attr("dy", ".71em")
          .style("text-anchor", "end");
  },

sample-json

  [
    {
      "date": "2013-06-01",
      "visits": 5
    },
    {
      "date": "2013-06-02",
      "visits": 10
    },
    {
      "date": "2013-06-03",
      "visits": 12
    },
    {
      "date": "2013-06-04",
      "visits": 8
    },
    {
      "date": "2013-06-05",
      "visits": 3
    }
  ]

error is on d3 line 74.
Error: Problem parsing d="MNaN,NaNLNaN,NaNLNaN,NaNLNaN,NaNLNaN,NaNLNaN,0LNaN,0LNaN,0LNaN,0LNaN,0Z"