The MouseEvent.region read-only property returns the id of the canvas hit region affected by the event. If no hit region is affected, null is returned. 
 The MouseEvent.region read-only property returns the id of the canvas hit region affected by the event. If no hit region is affected, null is returned. 
A DOMString representing the id of the hit region.
Example of using the event.region combined with CanvasRenderingContext2D.addHitRegion() method.
<canvas id="canvas"></canvas> <script> var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); ctx.beginPath(); ctx.arc(70, 80, 10, 0, 2 * Math.PI, false); ctx.fill(); ctx.addHitRegion({id: "circle"}); canvas.addEventListener("mousemove", function(event){ if(event.region) { console.log("hit region: " + event.region); } }); </script>
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
region | 
51  | 
79  | 
30  | 
No  | 
38  | 
No  | 
No  | 
51  | 
No  | 
41  | 
No  | 
No  | 
    © 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
    https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/region