How to use the annotations plugin with Rails 7 using Webpacker and Chartkick

how_to_use_annotations_plugin_with_rails_7.md

yarn add chartjs-plugin-annotation

Then edit app/javascript/application.js

import "chartkick/chart.js"

# Add these lines
import annotationPlugin from 'chartjs-plugin-annotation';
Chartkick.adapters[0].library.register(annotationPlugin);

See this pull request for more details

You can then add annotations using the following example format:

<%= line_chart data, library: {plugins: {annotation: {annotations: {line1: {type: "line", yMin: 2, yMax: 2}}}}} %>