chart = {
function draw()
{
var container = document.getElementById('visualization');
var items = new vis.DataSet([
{id: 1, content: 'item 1', start: '2014-04-20', title: 'tooltip for <i>item</i> <b>1</b>'},
{id: 2, content: 'item 2', start: '2014-04-14', title: 'tooltip for item 2'},
{id: 3, content: 'item 3', start: '2014-04-18', title: 'tooltip for item 3'},
{id: 4, content: 'item 4', start: '2014-04-16', end: '2014-04-19', title: 'tooltip for item 4'},
{id: 5, content: 'item 5', start: '2014-04-25', title: 'tooltip for item 5'},
{id: 6, content: 'item 6', start: '2014-04-27', type: 'point', title: 'tooltip for item 6'}
]);
var options = {
tooltip: {followMouse: true}
};
d3.select("#visualization").selectAll(".vis-timeline").remove()
var timeline = new vis.Timeline(container, items, options)
timeline.initialDrawDone = true
d3.selectAll(".vis-timeline").style("visibility", "visible")
return timeline
}
return draw()
}