title: c3.js cannot load lines value
body: <p>I post some code here.I don't know why the value of lines in old_chart can't update. 
  I have been searched all I can do.So I wish U guys can help me to figure out this.
  Thanks a lot!!</p>
  
  <pre><code>        &lt;script&gt;
      old_chart = c3.generate({
      bindto: '#chart',
       data: {
      columns: []
      },
       grid: {
      x: {
      show: true
      },
       y: {
      show: true,
       lines: []
      }
      }
      });
  
     $.ajax({type:"GET",
              url:"threshold",
              success: function(result){
                threshold_in_server = JSON.parse(result);
                input_threshold(threshold_in_server);
  
              }
      });
  
  input_threshold = function(threshold_in_server){
  
        old_chart.load({
          y: {
                lines: [{value:threshold_in_server[0] },
                        {value:threshold_in_server[1] }]
              }
         });
      };
      &lt;/script&gt;
  &lt;body&gt;
  &lt;div id='chart' style='position:absolute;top:25px'&gt;&lt;/div&gt;
  &lt;&gt;/body
  </code></pre>