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Debugging Node Applications with Google Chrome

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What is Debugging?

2:44 with Andrew Chalkley

Debugging is more than just logging out values. You'll discover more about what debugging is in this video.

To use git to download the project to your local machine, paste this to your terminal:

git clone https://github.com/treehouse-projects/reverse-app-node.git

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    [MUSIC] 0:00
    Hello world, Andrew here, JavaScript developer and teacher here at Treehouse. 0:04
    In this workshop, I'll show you the professional tools and 0:08
    techniques to debug your node.js applications. 0:11
    The process of debugging can be described as identifying errors in your code and 0:14
    removing them. 0:18
    What comes to mind when I say debugging? 0:19
    Maybe writing a console.log statement. 0:21
    [SOUND] Let's discuss some of the cons of using console.log as a way to check 0:24
    the state of your application. 0:29
    When building a web application, all HTTP requests get logged to the console. 0:31
    Attempting to log out your variables alongside the noise of the HTTP requests, 0:36
    may make debugging challenging when trying to find the value you're debugging. 0:41
    And what if the value logged out is exactly what you're expecting? 0:45
    You have to stop your application, write another console.log statement and 0:49
    then start up your application again. 0:53
    The process is clumsy and cumbersome. 0:56
    [SOUND] Which leads me to another issue. 0:58
    When you write a console.log statement, 1:01
    you're adding code to your application that you don't actually need. 1:03
    Your program doesn't require the console.log statements to function. 1:07
    In fact, committing the console.log statement to version control, isn't 1:11
    only frustrating to you but it may confuse other developers working on your project. 1:15
    Having seemingly random values logged out to the terminal raises questions, 1:20
    like what does this mean? 1:24
    Or, is this supposed to be here? 1:26
    In general, console.log can be problematic and 1:28
    you can overcome these problems by using proper debugging tools. 1:31
    [SOUND] Most environments have debugging tools that allow you to do a couple of 1:35
    important things. 1:39
    [SOUND] Firstly, it allows you to pause the execution of your program at 1:39
    specific points in the code. 1:44
    This allows you to inspect the contents of variables and 1:46
    modify their values while the program is still running. 1:49
    The application we'll be debugging is available on GitHub. 1:54
    I'll include the command to git clone it down to your local machine. 1:58
    It's an express application that was generated with the express generated 2:04
    command line tool and has been modified. 2:07
    After you've installed all the dependencies with npm install, 2:10
    you can start your application with npm start. 2:15
    If you visit localhost:3000 you see the application called Reversify. 2:20
    And it can reverse any string and it gives some examples. 2:25
    If I click on joel, it says blank 2:30
    reversed is leoj the original string is missing. 2:34
    We'll debug the application to see where our application is breaking. 2:40

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