kefir/src/one-source/to-property.js

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

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

const P = createProperty('toProperty', {
  _init({fn}) {
    this._getInitialCurrent = fn
  },

  _onActivation() {
    if (this._getInitialCurrent !== null) {
      const getInitial = this._getInitialCurrent
      this._emitValue(getInitial())
    }
    this._source.onAny(this._$handleAny) // copied from patterns/one-source
  },
})

export default function toProperty(obs, fn = null) {
  if (fn !== null && typeof fn !== 'function') {
    throw new Error('You should call toProperty() with a function or no arguments.')
  }
  return new P(obs, {fn})
}