Allowing date formatting for google chart tooltips via google.visualization.DateFormat

[alterx]

We're using chartkick for a project and we've come into the need of formatting the dates inside the tooltips.

Achieving this is as easy as adding a couple of lines to the following function using the formatter provided by google.

renderLineChart = function (element, series, opts) {
      waitForLoaded(function () {
        var options = jsOptions(series, opts);
        var data = createDataTable(series, "datetime");
        var formatter = new google.visualization.DateFormat({ 
             pattern: options.pattern 
        }); 
        formatter.format(data, 0);
        var chart = new google.visualization.LineChart(element);
        resize(function () {
          chart.draw(data, options);
        });
      });
    };

In general you could add the option to send the formatter as a parameter and apply it in the required functions.

[ankane]

Great, this solution looks nice and clean. I'm a bit torn at the moment - worried about breaking compatibility w/ Highcharts yet don't want to keep useful features out.

[alterx]

I think there's also an option to format the tooltips in Highcharts (http://api.highcharts.com/highcharts#Highcharts.dateFormat()).

I'll put something together and submit a pull request

[tagliala]

@ankane thanks for pointing me out this pull request

@alterx thanks I was looking for this one.

There is another thing that IMHO could be interesting in tooltips: format the "number" in the tooltip. Unfortunately I don't have time to dig into this library, so my workaround is an ugly rows[key][i] = toFloat(d[1].toFixed(2));

Refers to ankane/chartkick#46

[ankane]

Cleaning up old issues