MouseEvent.region

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.

var hitRegion = instanceOfMouseEvent.region

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>

• MouseEvent
• CanvasRenderingContext2D.addHitRegion()