Should calling chart.update() after modifying annotation options trigger changes?

I’m trying to change the line annotations I’ve created with updates to the datasets. Is it possible to modify the annotation options in place and then observe changes after chart.update()? I’m not currently seeing this but may be doing something wrong or should be replacing the chart.options.annotation object completely.

[veggiesaurus]

I had some trouble with getting the options to propagate correctly, but in the end, this worked for me:

chart.annotation.elements['my-annotation-id'].options.value = newValue;
chart.update();

See this jsfiddle for an example. [Note that this is actually a test for a PR I’ve worked on, so don’t expect chart.render() to update annotations until #116 is merged]

[frederikheld]

For everyone who’s fiddling around with this like me: It’s also possible to update the content of an annotation label in the same way 😃

// update data:
myChart.data.datasets = formatChartData(newData)

// update mean annotation:
myChart.annotation.elements['mean-value'].options.value = calculateMean(newData)
myChart.annotation.elements['mean-value'].options.label.content = 'mean = ' + Math.round(calculateMean(newData) * 100) / 100

// re-render chart:
myChart.update()

In this example I’m drawning an horizontal line that shows the mean value of a bar chart.