Using the Chrome Debugger in the following way:
console.dir(element);
On the console the data-type is called a "PropertyBag". I would have expected "Object".
What special kind of object is a "PropertyBag"?
I have never read that term in JavaScript before ...
As you said in the above comments, you are using some code written by somebody else (or a custom framework) and element is just an instance of a custom class. For example, the PropertyBag class exists in cesiumjs.
If the object is an instance of a class (not a simple object, really a class with a constructor), if you use console.log on that item, you'll get the class name in the console (at least in Chrome) and a little arrow to expand it. You can copy/paste the following code in the console to test the behavior.
class User {
constructor(name) {
this.name = name;
}
sayHi() {
alert(this.name);
}
}
let user = new User("John");
console.log(user);
Cheers!