Concatenates the observable sequences or Promises obtained by running the specified result selector for each element in source.
There is an alias for this method called
forIn for browsers <IE9
sources(Array): An array of values to turn into an observable sequence.
Function): A function to apply to each item in the sources array to turn it into an observable sequence. The resultSelector 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
Observable): An observable sequence from the concatenated observable sequences or Promises.