navigo/lib/es/middlewares/checkForLeaveHook.js

A simple vanilla JavaScript router

import Q from "../Q";
import { undefinedOrTrue } from "../utils";
export default function checkForLeaveHook(context, done) {
  var instance = context.instance;

  if (!instance.lastResolved()) {
    done();
    return;
  }

  Q(instance.lastResolved().map(function (oldMatch) {
    return function (_, leaveLoopDone) {
      // no leave hook
      if (!oldMatch.route.hooks || !oldMatch.route.hooks.leave) {
        leaveLoopDone();
        return;
      }

      var runHook = false;
      var newLocationVSOldMatch = context.instance.matchLocation(oldMatch.route.path, context.currentLocationPath, false);

      if (oldMatch.route.path !== "*") {
        runHook = !newLocationVSOldMatch;
      } else {
        var someOfTheLastOnesMatch = context.matches ? context.matches.find(function (match) {
          return oldMatch.route.path === match.route.path;
        }) : false;
        runHook = !someOfTheLastOnesMatch;
      }

      if (undefinedOrTrue(context.navigateOptions, "callHooks") && runHook) {
        Q(oldMatch.route.hooks.leave.map(function (f) {
          // just so we match the Q interface
          return function (_, d) {
            return f(function (shouldStop) {
              if (shouldStop === false) {
                context.instance.__markAsClean(context);
              } else {
                d();
              }
            }, context.matches && context.matches.length > 0 ? context.matches.length === 1 ? context.matches[0] : context.matches : undefined);
          };
        }).concat([function () {
          return leaveLoopDone();
        }]));
        return;
      } else {
        leaveLoopDone();
      }
    };
  }), {}, function () {
    return done();
  });
}