redux-promise-middleware-es3/node_modules/history/modules/runTransitionHook.js

Redux middleware for handling promises and optimistic updates with ES3 support

import warning from 'warning'

function runTransitionHook(hook, location, callback) {
  const result = hook(location, callback)

  if (hook.length < 2) {
    // Assume the hook runs synchronously and automatically
    // call the callback with the return value.
    callback(result)
  } else {
    warning(
      result === undefined,
      'You should not "return" in a transition hook with a callback argument; call the callback instead'
    )
  }
}

export default runTransitionHook