Javascript onClick function for google's GeoChart

Question

I am trying to display a map using google's geochart https://developers.google.com/chart/interactive/docs/gallery/geochart

The map displays the data and specified countries fine, but I can't work out how assign a link onClick to each specific country, or even get any onClick function for the countries.

This link describes the Events 'regionClick' and 'select', which sounds like part of what I need, though I'm not sure how these will trigger my link function...Im new to javascript. With 'select' there seems to be a method to 'getSelected'

<scripts type='text/javascript'>
  google.load('visualization', '1', {'packages': ['geomap']});
  google.setOnLoadCallback(drawMap);
  function drawMap() {
    var data = google.visualization.arrayToDataTable([
      ['Country', 'Projects'],
      ['Russia', 3],
      ['France', 2],
      ['Spain', 4]
    ]);

    var options = {};
    options['dataMode'] = 'regions';
    options['width'] = '834px';
    options['height'] = '521px';

    var container = document.getElementById('map_canvas');
    var chart = new google.visualization.GeoChart(container);
    chart.draw(data, options);
  };


  function myClickHandler(){
    var selection = chart.getSelection();

    for (var i = 0; i < selection.length; i++) {
      var item = selection[i];
      if (item.row != null && item.column != null) {
        message += '{row:' + item.row + ',column:' + item.column + '}';
      } else if (item.row != null) {
        message += '{row:' + item.row + '}';
      } else if (item.column != null) {
        message += '{column:' + item.column + '}';
      }
    }
    if (message == '') {
      message = 'nothing';
    }
    alert('You selected ' + message);
  }
</script>

Any help or direction appreciated.

Answer 1

There are a couple of things you need to do. First, since your function myClickHandler references the object chart , its needs to be in the same scope as chart , so you have to move it inside drawMap . Second, you need to create a 'click' event handler for the chart that uses the myClickHandler function. Here's what the code should look like:

function drawMap() {
    var data = google.visualization.arrayToDataTable([
        ['Country', 'Projects'],
        ['Russia', 3],
        ['France', 2],
        ['Spain', 4]
    ]);

    var options = {
        dataMode: 'regions',
        width: 834,
        height: 521
    };

    var container = document.getElementById('map_canvas');
    var chart = new google.visualization.GeoChart(container);

    function myClickHandler(){
        var selection = chart.getSelection();
        var message = '';
        for (var i = 0; i < selection.length; i++) {
            var item = selection[i];
            if (item.row != null && item.column != null) {
                message += '{row:' + item.row + ',column:' + item.column + '}';
            } else if (item.row != null) {
                message += '{row:' + item.row + '}';
            } else if (item.column != null) {
                message += '{column:' + item.column + '}';
            }
        }
        if (message == '') {
            message = 'nothing';
        }
        alert('You selected ' + message);
    }

    google.visualization.events.addListener(chart, 'select', myClickHandler);

    chart.draw(data, options);
}
google.load('visualization', '1', {packages: ['geochart'], callback: drawMap});

jsfiddle: http://jsfiddle.net/asgallant/6dP28/