StartWith in RxJS: Conditional Implementation

My objective here is to utilize startWith conditionally based on the value of another observable.

I attempted using mergeMap instead of map and encapsulated the return values with 'of' but it didn't yield the desired results.

fromEvent(element.nativeElement,'click').pipe(
    withLatestFrom(this.isMobileView$),
    map(([event, isMobileView]) => {
        if (isMobileView) {
            // perform certain actions
            return false;
        } else {
            // perform other actions
            // return a boolean variable
            return this._drawer.opened;
        }// TODO: consider nativescript code here
    }),
    // I aim to incorporate 'isMobileView' in my startWith
    //   something like startWith(!isMobileView)
    startWith(true),

);

Expecting the sequence of observables to begin with false when in mobile view and true otherwise.

Answer №1

If you want to define it in a different way, consider the following code snippet:

const handleClick = this.isMobileView$.pipe(
  switchMap(isMobileView => 
    fromEvent(element.nativeElement,'click').pipe(
      map(event => {
        if (isMobileView) {
          // perform specific actions for mobile view
          return false;
        } else {
          // perform other actions and return boolean variable
          return this._drawer.opened;
        }
      }),
      startWith(!isMobileView)
  )
);

By using this approach, you will be simply re-subscribing whenever isMobileView$ emits, without impacting your previous click subscription significantly.

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