kefir/src/one-source/take.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 mixin = {
  _init({n}) {
    this._n = n
    if (n <= 0) {
      this._emitEnd()
    }
  },

  _handleValue(x) {
    if (this._n === 0) {
      return
    }
    this._n--
    this._emitValue(x)
    if (this._n === 0) {
      this._emitEnd()
    }
  },
}

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

export default function take(obs, n) {
  return new (obs._ofSameType(S, P))(obs, {n})
}