Function intervalToMs

intervalToMs(interval, defaultNumber?): number
Return the millisecond value of an Interval.
```
intervalToMs(100); // 100
intervalToMs({ millis: 100 }); // 100
```
Use defaultNumber to return a default in the case of undefined or invalid input.
```
intervalToMs(undefined);      // throws error
intervalToMs(undefined, 100); // 100
```
If no default is provided, an exception is thrown.
Parameters
- interval: undefined | Interval
  Interval
- OptionaldefaultNumber: number
  Default value if interval is undefined or invalid
Returns number
Milliseconds