Suppose I have this time

```
'2018-08-03T15:53:57.000Z'

```

I need to convert only the time part to `milliseconds`

I tried this but didn't work and throws error

```
moment.utc("2018-08-03T15:53:57.000Z").format('HH:mm:ss').milliseconds()

```

**Error** 

```
TypeError: (0 , _moment2.default)(...).format(...).milliseconds is not a function

```

Can someone please help how can I convert only time to millisecond?

Thank you!!!