The isPointInRange() method of the Range interface determines whether a specified point is within the Range. The point is specified by a reference node and an offset within that node. It is equivalent to calling Range.comparePoint() and checking if the result is 0.
isPointInRange(referenceNode, offset)referenceNodeThe Node that the offset is relative to.
offsetAn integer greater than or equal to zero describing the position inside referenceNode of the point to be checked. If referenceNode is a Node of type Text, Comment, or CDATASection, then offset is the number of characters from the start of referenceNode. For other Node types, offset is the number of child nodes from the start of the referenceNode.
A boolean.
const text = new Text("0123456789");
const thisRange = new Range();
thisRange.setStart(text, 1);
thisRange.setEnd(text, 6);
thisRange.isPointInRange(text, 3); // true
thisRange.isPointInRange(text, 0); // false
thisRange.isPointInRange(text, 6); // true
thisRange.isPointInRange(text, 7); // false