kefir/src/one-source/delay.js

Reactive Programming library for JavaScript inspired by Bacon.js and RxJS with focus on high performance and low memory usage

import {createStream, createProperty} from '../patterns/one-source'

const END_MARKER = {}

const mixin = {
  _init({wait}) {
    this._wait = Math.max(0, wait)
    this._buff = []
    this._$shiftBuff = () => {
      const value = this._buff.shift()
      if (value === END_MARKER) {
        this._emitEnd()
      } else {
        this._emitValue(value)
      }
    }
  },

  _free() {
    this._buff = null
    this._$shiftBuff = null
  },

  _handleValue(x) {
    if (this._activating) {
      this._emitValue(x)
    } else {
      this._buff.push(x)
      setTimeout(this._$shiftBuff, this._wait)
    }
  },

  _handleEnd() {
    if (this._activating) {
      this._emitEnd()
    } else {
      this._buff.push(END_MARKER)
      setTimeout(this._$shiftBuff, this._wait)
    }
  },
}

const S = createStream('delay', mixin)
const P = createProperty('delay', mixin)

export default function delay(obs, wait) {
  return new (obs._ofSameType(S, P))(obs, {wait})
}