Instructor: 0:01 We'll start by importing a Vue component we'll call failedAuth, which will act as the page we send our users to if they're unauthenticated and unable to access the place they're attempting to go. In order to use this, we need to create a route record that can send us there. We'll set the path to failed and the component to failedAuth.
0:28 Before we can check whether or not we want to send our user somewhere, we need to know if they're authenticated. We'll create a function that will return a Boolean true or false value for the moment. This is just a dummy function.
0:46 On our router, we're going to use a hook, the function beforeEach(). This will be triggered every time a user tries to navigate to a page. BeforeEach() takes the arguments to, from and next.
1:06 We'll use the two argument in order to match against the route record and see whether the page they're trying to navigate to requiresAuth. We can do this because we've set requiresAuth as metadata on our routes.
1:33 If we find that this route requires authentication, we'll add a new check, is our user authenticated? If they are, we'll send them where they want to go. We'll use the next argument, which is a function that will complete the logical loop.
1:56 Otherwise, we want to send them elsewhere. If we call next with false, that will send them to from, back from where they came. In our case, we'd rather end the logic by sending them to our failed page. Similarly, we could send them to login or somewhere else.
2:21 Finally, we need to add an else statement if the record does not require auth. We'll use next to end the navigation. If we navigate to egghead, they're not authenticated so they can't get there. The navigation guard is triggered because the user has tried to navigate to a new page. RequiresAuth is set to true on the egghead route record, so we drop into the first set of logic.
2:51 The isAuthenticated() function results to false, which sends us to the else block. There we call the next function with the failed route path. That sends us to the failed route record, as we can see. Next, we'll change our isAuthenticated() function to return true.
3:14 If we try and navigate to egghead again, it will be successful. That's because it's going into if isAuthenticated resolving to true and triggering the next function, which ends our navigation guard and sends the user to the URL they're attempting to navigate to.
3:36 We can see that our beforeEach navigation guard is working as anticipated.