anychart.onDocumentReady(function () {
var chart = anychart.area();
var series = chart.splineArea([
{x: 'January', value: 125},
{x: 'February', value: -132},
{x: 'March', value: 141},
{x: 'April', value: -158},
series.negativeFill(function () {
return this.sourceColor + ' 0.3';
chart.title('Set negative fill parameters as a function');
chart.container('container');