Function onChildAttachedTo

onChildAttachedTo(target, fn, options?): ((runDetachDisposers) => void)
Runs a callback everytime a new object is attached to a given node. The callback can optionally return a disposer which will be run when the child is detached.

The optional options parameter accepts and object with the following options:
- deep: boolean (default: false) - true if the callback should be run for all children deeply or false if it it should only run for shallow children.
- fireForCurrentChildren: boolean (default: true) - true if the callback should be immediately called for currently attached children, false if only for future attachments.
Returns a disposer, which has a boolean parameter which should be true if pending detachment callbacks should be run or false otherwise.
Parameters
- target: (() => object)
  Function that returns the object whose children should be tracked.
  - - (): object
    - Returns object
- fn: ((child) => void | (() => void))
  Callback called when a child is attached to the target object.
  - - (child): void | (() => void)
    - Parameters
      child: object
      Returns void | (() => void)
- Optional options: {
  deep?: boolean;
  fireForCurrentChildren?: boolean;
  }
  - Optional deep?: boolean
  - Optional fireForCurrentChildren?: boolean
Returns ((runDetachDisposers) => void)
- - (runDetachDisposers): void
  - Parameters
    - runDetachDisposers: boolean
    Returns void