Rx.Observable.prototype.takeWhile(predicate, [thisArg])

Returns elements from an observable sequence as long as a specified condition is true.

参数

1. predicate (Function): A function to test each source element for a condition. The callback is called with the following information:
   1. the value of the element
   2. the index of the element
   3. the Observable object being subscribed
2. [thisArg] (Any): Object to use as this when executing callback.

返回值

(Observable): An observable sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes.

例