bind-watch.js

module.exports = bindWatch

function bindWatch (obs, handler) {
  if (typeof handler === 'function') {
    return obs(handler.bind(obs))
  } else if (handler instanceof Object) {
    var removeListeners = Object.keys(handler).map(watchKey, {
      obs: obs,
      handlers: handler
    })
    return function unwatch () {
      while (removeListeners.length) {
        removeListeners.pop()()
      }
    }
  }
}

function watchKey (key) {
  var obs = this.obs[key]
  var handler = this.handlers[key]
  if (typeof obs === 'function' && typeof handler === 'function') {
    return obs(handler.bind(obs))
  }
}