RxJS：shareReplay如何不存储空值？

Question

let btn = document.getElementById('btn')
let input = document.getElementById('input')

let input$ = defer(() => of(input.value)).pipe(
  tap(v => console.log('tap', v)),
  filter(v => v),
  shareReplay(1)
)
let click$ = fromEvent(btn, 'click').pipe(
  switchMap(_ => input$)
)
click$.subscribe(v => console.log(v))

我只想在输入值不为null时存储input $。 现在的问题是，如果输入的值最初为null，则它已经存储，过滤器无法正常工作。
演示链接

Answer 1

您可以尝试一下，在输入$之前输入if-else

let btn = document.getElementById('btn')
let input = document.getElementById('input')
if (input != null){
  let inputValue = input
}

let input$ = defer(() => of(inputValue.value)).pipe(
  tap(v => console.log('tap', v)),
  filter(v => v),
  shareReplay(1)
)
let click$ = fromEvent(btn, 'click').pipe(
  switchMap(_ => input$)
)
click$.subscribe(v => console.log(v))