Function onParameterChange

onParameterChange(parameterName, fn): string
JMap.History.onParameterChange

You can attach a listener that listen for url hash params change.

The function returns the listener id that can be used after to remove the listener.
Parameters
- parameterName: string
  the name of the parameter
- fn: ((oldValue, newValue) => void)
  the function that will be processed when the property changed
  - - (oldValue, newValue): void
    - Parameters
      oldValue: string
      newValue: undefined | string
      Returns void
Returns string
the listener id, can be used to remove the listener with JMap.History.removePropertyChangeListener
Throws
Error if parameterName is not a valid string or fn is not a function

Example
```
const listenerId = JMap.History.onParameterChange("ngProjectId", (oldValue, newValue) => {
   console.log(`In the url hash the parameter "ngProjectId" has changed from "${oldValue}" to "${newValue}"`)
})
```