'Modified',Work only once

GoJS
1

I set up this listener, but it only works the first time，I don’t know why。
I’ve set addModelChangedListener, and that works. But I still want to know about Modified.
this.myDiagram?.addDiagramListener(‘Modified’, (e) => {
if (this.myDiagram) {
console.log(this.myDiagram.isModified);
this.myDiagram.isModified = false;
}
const iter = this.myDiagram?.selection.iterator;
iter?.iterator.each((node) => {
console.log(node.data);
this.event.editPosition(node.data);
});
});

2

Note that the documentation https://gojs.net/latest/api/symbols/Diagram.html#isModified states:

A “Modified” DiagramEvent listener must not modify this Diagram or its Model.

If you programmatically set Diagram.isModified to false during a transaction in which some modifications have occurred, Diagram.isModified will remain true until after the transaction has finished and the “Modified” DiagramEvent will be raised then.