@rashedk,
To update the y value of a datapoint using a dropdown menu you need to update the chart options / data based on the options selected from the dropdown list. Please check the code snippet below.
var country = document.getElementById("country");
country.addEventListener( "change", function(){
for(var i = 0; i < chart.options.data[0].dataPoints.length; i++) {
if(country.options[country.selectedIndex].text === chart.options.data[0].dataPoints[i].label)
chart.options.data[0].dataPoints[i].y = Number(country.options[country.selectedIndex].value);
}
chart.render();
});
Please take a look at this JSFiddle for a working example.
—
Thangaraj Raman
Team CanvasJS