Function replaceAtIndex

packages/core/src/StateUtils.js:153–173

* Replace a route by a index. * Note that this moves the index to the position to where the new route in the * stack is at.

(state, index, route)

   * stack is at.
   */
  replaceAtIndex(state, index, route) {
    invariant(
      !!state.routes[index],
      'invalid index %s for replacing route %s',
      index,
      route.key
    );

    if (state.routes[index] === route && index === state.index) {
      return state;
    }

    const routes = state.routes.slice();
    routes[index] = route;

    return {
      ...state,
      index,
      routes,
    };
  },

  /**
   * Resets all routes.