skipFilter

Skip filter operator, determines whether to skip data emissions based on a filter function.

Type Definition

type skipFilter = (filter: (time: number) => boolean) => (observable$: Observable) => Observable

Parameters

• filter: Filter function that receives the current emission count and returns a boolean
  • Parameter: time - Emission count starting from 1
  • Return: true to emit data, false to skip

Details

• Takes a filter function parameter that receives the current emission count and returns a boolean
• Emits data when filter function returns true, skips when false
• Uses internal counter to track emission count, starting from 1
• Works with all data types, including successful and failed states of Promise

Examples

Scenario 1: Skip odd-numbered emissions

import { $, skipFilter } from 'fluth'

const stream$ = $()

// Use skipFilter operator, only accept even-numbered emissions
const filtered$ = stream$.pipe(skipFilter((time) => time % 2 === 0))

filtered$.then((value) => {
  console.log('Filtered value:', value)
})

// Emit data
stream$.next('first') // 1st time, skipped, no output
stream$.next('second') // 2nd time, output: Filtered value: second
stream$.next('third') // 3rd time, skipped, no output
stream$.next('fourth') // 4th time, output: Filtered value: fourth

Scenario 2: Skip first N emissions

import { $, skipFilter } from 'fluth'

const stream$ = $()

// Skip first 3 emissions
const filtered$ = stream$.pipe(skipFilter((time) => time > 3))

filtered$.then((value) => {
  console.log('After skipping first 3:', value)
})

stream$.next('first') // 1st time, skipped
stream$.next('second') // 2nd time, skipped
stream$.next('third') // 3rd time, skipped
stream$.next('fourth') // 4th time, output: After skipping first 3: fourth
stream$.next('fifth') // 5th time, output: After skipping first 3: fifth

Scenario 3: Emit every Nth time

import { $, skipFilter } from 'fluth'

const stream$ = $()

// Emit every 3rd time (3rd, 6th, 9th...)
const filtered$ = stream$.pipe(skipFilter((time) => time % 3 === 0))

filtered$.then((value) => {
  console.log('Every 3rd emission:', value)
})

for (let i = 1; i <= 10; i++) {
  stream$.next(`value${i}`)
}
// Output:
// Every 3rd emission: value3
// Every 3rd emission: value6
// Every 3rd emission: value9

Relationship with Other APIs

• vs skip operator: skip skips a fixed number of initial emissions, while skipFilter can skip based on complex conditions
• vs filter operator: filter filters based on data values, while skipFilter filters based on emission count