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Express Basics

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Handling 404 Errors

2:34 with Andrew Chalkley and Joel Kraft

Now that we have a custom error handler, let's add a middleware function to handle 404 errors, and send them to the error handler.

Documentation

Fun 404 Pages

You'll need to type these addresses manually! 404 Examples

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    A 404 signals that the user requested a route that doesn't exist. 0:00
    Remember, when an app gets a request, 0:05
    it will go from one app.use call to the next looking for a match. 0:08
    If it gets to the end without finding a route and there are no errors, 0:13
    Express' native handler will send a 404 back to the client with some plain text. 0:19
    If we catch the request before it gets to the end of the line, 0:26
    we can send users a better page. 0:30
    Check out Treehouse's 404 page, or Lego's, 0:33
    or my personal favorite, GitHub. 0:39
    We can give our users a less scary page too. 0:42
    Let's write some middleware to handle 404 errors in our app. 0:46
    We want to access the request at the end of our app and before the error handler. 0:51
    So let's call app.use here. 0:58
    We're going to use the error handler we wrote in the last video 1:10
    to handle the actual error. 1:13
    This middleware will just be responsible for 1:16
    creating the error object and handing off to the error handler. 1:19
    I'll create a new error, Not found. 1:25
    Then I'll set the error status code, 1:36
    To 404, Before parsing it to the next function. 1:42
    Now, any requests that makes it this far will run this function and 1:53
    trigger the error handler. 1:58
    The error handler itself will send the page out to the user in that event. 2:01
    Let's try it out. 2:06
    In the browser, I'll request a route that doesn't exist. 2:08
    Voila, now when our users go astray, they will get a friendlier notice. 2:16
    We've covered the basics of Express now, well done. 2:22
    Let's cement your knowledge in the remainder of this course by 2:25
    finishing our flash card application. 2:28
    Are you ready to apply your knowledge? 2:30
    See you there. 2:33

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