@react-navigation/core/lib/module/useOnPreventRemove.js

Core utilities for building navigators

"use strict";

import * as React from 'react';
import { NavigationBuilderContext } from "./NavigationBuilderContext.js";
import { NavigationRouteContext } from "./NavigationRouteContext.js";
const VISITED_ROUTE_KEYS = Symbol('VISITED_ROUTE_KEYS');
export const shouldPreventRemove = (emitter, beforeRemoveListeners, currentRoutes, nextRoutes, action) => {
  const nextRouteKeys = nextRoutes.map(route => route.key);

  // Call these in reverse order so last screens handle the event first
  const removedRoutes = currentRoutes.filter(route => !nextRouteKeys.includes(route.key)).reverse();
  const visitedRouteKeys =
  // @ts-expect-error: add this property to mark that we've already emitted this action
  action[VISITED_ROUTE_KEYS] ?? new Set();
  const beforeRemoveAction = {
    ...action,
    [VISITED_ROUTE_KEYS]: visitedRouteKeys
  };
  for (const route of removedRoutes) {
    if (visitedRouteKeys.has(route.key)) {
      // Skip if we've already emitted this action for this screen
      continue;
    }

    // First, we need to check if any child screens want to prevent it
    const isPrevented = beforeRemoveListeners[route.key]?.(beforeRemoveAction);
    if (isPrevented) {
      return true;
    }
    visitedRouteKeys.add(route.key);
    const event = emitter.emit({
      type: 'beforeRemove',
      target: route.key,
      data: {
        action: beforeRemoveAction
      },
      canPreventDefault: true
    });
    if (event.defaultPrevented) {
      return true;
    }
  }
  return false;
};
export function useOnPreventRemove({
  getState,
  emitter,
  beforeRemoveListeners
}) {
  const {
    addKeyedListener
  } = React.useContext(NavigationBuilderContext);
  const route = React.useContext(NavigationRouteContext);
  const routeKey = route?.key;
  React.useEffect(() => {
    if (routeKey) {
      return addKeyedListener?.('beforeRemove', routeKey, action => {
        const state = getState();
        return shouldPreventRemove(emitter, beforeRemoveListeners, state.routes, [], action);
      });
    }
  }, [addKeyedListener, beforeRemoveListeners, emitter, getState, routeKey]);
}
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