areaOpacity: 0 is the option I think you are looking for...
HOWEVER, this option only works on Area charts, not Line charts.
not sure it will work for you.
see following Area chart, with the fill color removed.
google.charts.load('current', {
packages: ['controls']
}).then(function () {
var data = new google.visualization.DataTable();
data.addColumn('number', 'x');
data.addColumn('number', 'y');
data.addRows([
[0, 4000],
[1, 3800],
[2, 5600],
[3, 5800],
[4, 5400],
[5, 5000]
]);
var chart = new google.visualization.ChartWrapper({
chartType: 'AreaChart',
containerId: 'chart_div',
dataTable: data,
options: {
areaOpacity: 0
}
});
chart.draw();
});
<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>
see following Line chart, with the fill color added (doesn't work).
google.charts.load('current', {
packages: ['controls']
}).then(function () {
var data = new google.visualization.DataTable();
data.addColumn('number', 'x');
data.addColumn('number', 'y');
data.addRows([
[0, 4000],
[1, 3800],
[2, 5600],
[3, 5800],
[4, 5400],
[5, 5000]
]);
var chart = new google.visualization.ChartWrapper({
chartType: 'LineChart',
containerId: 'chart_div',
dataTable: data,
options: {
areaOpacity: 0.3
}
});
chart.draw();
});
<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>
and just for reference, see following Area chart, with the fill color added.
google.charts.load('current', {
packages: ['controls']
}).then(function () {
var data = new google.visualization.DataTable();
data.addColumn('number', 'x');
data.addColumn('number', 'y');
data.addRows([
[0, 4000],
[1, 3800],
[2, 5600],
[3, 5800],
[4, 5400],
[5, 5000]
]);
var chart = new google.visualization.ChartWrapper({
chartType: 'AreaChart',
containerId: 'chart_div',
dataTable: data,
options: {
areaOpacity: 0.3
}
});
chart.draw();
});
<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>