@unixssh,
Datapoint accepts x-value and y-value with optional label and z-value. In your case, you seem to be passing a property called ‘w’ instead of ‘y’ on clicking update button. Changing chart.options.data[0].dataPoints[i] = {x:date1, w:w}; to chart.options.data[0].dataPoints[i] = {x:date1, y:w}; should work fine in your case.
If you are still facing issue, kindly create JSFiddle reproducing the issue you are facing and share it with us, so that we can look into the code / chart-options being used, understand the scenario better and help you out.
—
Vishwas R
Team CanvasJS
