Returns elements from an observable sequence as long as a specified condition is true.
Function): A function to test each source element for a condition. The callback is called with the following information:
- the value of the element
- the index of the element
- the Observable object being subscribed
Any): Object to use as this when executing callback.
Observable): An observable sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes.