react-router-last-location/src/prevent.ts

Provides access to the last location in react + react-router (v4.x) apps. Useful for handling internal routing. Easily prevent leaving your app by users.

import { RouteComponentProps } from 'react-router-dom';

type RRLocation = RouteComponentProps['location'] & { [key: string]: any };
type LiteLocation = Pick<RRLocation, Exclude<keyof RRLocation, 'state'>>;

/**
 * I could only check `key` here but according to:
 * @see https://reacttraining.com/react-router/web/api/location
 * `key` property is not available when HashHistory is used.
 */
const props = ['key', 'pathname', 'search', 'hash'];
const isEqual = (a: LiteLocation, b: LiteLocation) => props.every(prop => a[prop] === b[prop]);

const prevented: LiteLocation[] = [];

export const prevent = (location: RRLocation) => {
  const { state, ...rest } = location;
  prevented.push(rest);
};

export const hasBeenPrevented = (location: RRLocation) =>
  prevented.some(preventedLocation => isEqual(location, preventedLocation));

export const shouldPrevent = (location: RRLocation): boolean =>
  Boolean(location.state && location.state.preventLastLocation);