Function isCategory

isCategory<T>(obj, category, checkAncestors?): obj is T
Use instead of instanceof as a more flexible type guard.
Type Parameters
- T
Parameters
- obj: any
  
  check if this object's CATEGORY matches the provided category.
- category: string
  
  a string representing a category of VexFlow objects.
- checkAncestors: boolean = true
  
  defaults to true, so we walk up the prototype chain to look for a matching CATEGORY. If false, we do not check the superclass or other ancestors.
Returns obj is T
true if obj has a static CATEGORY property that matches category.