The width property of the VTTRegion interface represents the width of the region, as a percentage of the video's width.
A number in the range 0 to 100 inclusive, representing the width of the region as a percentage of the video's width. The default is 100.
IndexSizeError DOMExceptionThrown when set to a value that is negative or greater than 100.
In the following example, a new VTTRegion is created, then the value of width is set to 50. The value is then printed to the console.
const region = new VTTRegion();
region.width = 50; // Set the region to 50% of the video's width
console.log(region.width);