This line chart shows the price of Apple stock with a tooltip. Data: Yahoo Finance This chart emits input events and exposes a value (the focused data); you can listen for these events (e.g., `chart.addEventListener("input", …)`) to support interaction such as coordinated views. On Observable, you can even define a reactive value by declaring the chart as a view or using Generators.input as below;
![Line Chart, Tooltip](https://cdn-ak-scissors.b.st-hatena.com/image/square/9a7c2bd905902a939fc24fcc2f4da4983a328b54/height=288;version=1;width=512/https%3A%2F%2Fstatic.observableusercontent.com%2Fthumbnail%2F916a57cecb4b2596a80e2eeb13a3bf778e8e7513d65d4c14214ab851bbd9f952.jpg)