Question

On page jqPlot there is an example of dragging data point on jqPlot chart.

How can I submit (e.g. with jQuery ajax) to server changed values? Are changed (current) values stored somewhere in jqplot object?

Answer 1

The hardest thing here is knowing when the user drags a point, not getting the data afterward. I recommend you use a postDrawSeries hook like so:

$(document).ready(function () {

  // set up plot
  $.jqplot.config.enablePlugins = true;

  s1 = [['23-May-08',1],['24-May-08',4],['25-May-08',2],['26-May-08', 6]];

  plot1 = $.jqplot('chart1',[s1],{
     title: 'Highlighting, Dragging, Cursor and Trend Line',
     axes: {
         xaxis: {
             renderer: $.jqplot.DateAxisRenderer,
             tickOptions: {
                 formatString: '%#m/%#d/%y'
             },
             numberTicks: 4
         },
         yaxis: {
             tickOptions: {
                 formatString: '$%.2f'
             }
         }
     },
     highlighter: {
         sizeAdjust: 10,
         tooltipLocation: 'n',
         tooltipAxes: 'y',
         tooltipFormatString: '<b><i><span style="color:red;">hello</span></i></b> %.2f',
         useAxesFormatters: false
     },
     cursor: {
         show: true
     }
  });

  // add our hook, to fire after a series update
  $.jqplot.postDrawSeriesHooks.push(updatedSeries);

  function updatedSeries(sctx, options) {
    console.log(plot1.series[0].data); //data for the series is here
  }

});

Output on every drag is (containing the updated data point):

[
Array[2]
, 
Array[2]
, 
Array[2]
, 
Array[2]
]

Here’s an example. (You’ll have to cache the jqPlot js files in your browser since they do not allow hotlinking.)

You’ll have to implement some sort of timer to wait for 5 seconds or so before calling your ajax since the postdrawseries hook fires on EVERY drag event. That shouldn’t be too hard though.