Add tooltips to a Google Line Chart with multiple data series - with simplified test case and screenshot

Question

I have a Google Line Chart with 2 data series - Row A and Row B:

Answer 1

You can use a DataView to create the tooltip columns for you. This code snippet will dynamically create a tooltip column in the DataView for every data series:

var columns = [0];
for (var i = 1; i < x.getNumberOfColumns(); i++) {
    columns.push(i);
    columns.push({
        type: 'string',
        properties: {
            role: 'tooltip'
        },
        calc: (function (j) {
            return function (dt, row) {
                return dt.getColumnLabel(j) + ': x=' + dt.getValue(row, 0) + ' y=' + dt.getValue(row, j)
            }
        })(i)
    });
}
var view = new google.visualization.DataView(x);
view.setColumns(columns);

See the working example here: http://jsfiddle.net/asgallant/xWwxP/