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There's more to debugging Node.js programs than logging values in your code. In general, console.log can be problematic, but you can overcome those problems using the Visual Studio Code editor's built-in debugger.
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[MUSIC]
0:00
Debugging is the process of identifying
and fixing defects in a program.
0:09
When you think about debugging one method
that might come to mind is writing
0:13
console.log statements to try to
identify what's gone wrong in your code.
0:17
The console.log method is native to Node
JS, where it prints to the terminal.
0:21
Similar to the way it prints to the web
browser's console when used in client side
0:25
JavaScript.
0:29
With console.log you can, for example,
take snapshots of variables at specific
0:30
moments in your program, which gives you
insight into where things are going wrong.
0:34
While console.log may be a tried,
and true, and
0:38
seemingly reliable approach to debugging.
0:41
It's not the most ideal or efficient way
to check the state of your application and
0:43
debug your program.
0:48
For example,
when building Node applications,
0:49
all HTTP requests get
logged to the console.
0:52
This generates a lot of
noise in the terminal,
0:54
which can make it difficult to locate the
values you're trying to log and evaluate.
0:57
And what if the log value is
exactly what you were expecting?
1:01
You have to stop your application,
1:04
then figure out where to write
another console.log statement.
1:06
This process can get unwieldy.
1:09
In addition, when u write a console.log
you are adding code to your application.
1:11
Because your program technically doesn't
require the console.log statement to
1:16
function.
1:20
And when you're done debugging,
1:20
you'll usually have to go back to your
program and remove all the log statements.
1:22
Not removing them means, you might commit
those log statements to version control.
1:26
Which can lead to
confusion later when you or
1:30
other developers working on
the project revisit the code.
1:32
In general,
console.log can be problematic.
1:35
But you can overcome those problems
by using proper debugging tools.
1:37
There are other more capable and
efficient ways to debug and node.
1:41
I'm Guil,
a JavaScript instructor here at Treehouse.
1:44
In this workshop, I'll teach you how
to debug node applications using
1:48
the Visual Studio Code
editors built in debugger.
1:51
There's more to debugging node programs
than just logging out values in your code.
1:54
VS code's reliable debugger provides
many useful features including a way
1:59
to pause the execution of a program
at specified points in the code.
2:04
This allows you to inspect the contents
of variables, and modify their values
2:08
while the program is running to
check how it affects the program.
2:12
You're able to execute or
run a program one line at a time.
2:15
That way you can see what's happening
inside your program as it runs line
2:19
by line.
2:23
And once you identify the problem,
you can quickly fix the defect and
2:23
test your fix until you've got your
program working the way you want it to.
2:27
You can do all these and
more directly in the VS Code editor.
2:31
The application we will use in this
workshop is an express application that
2:35
was generated using the express generator
command line tool and slightly modified.
2:40
This simple application called Reversify
takes any string from URL and reverses it.
2:44
And it provides a few examples.
2:50
Notice, that when I click on mali,
for instance,
2:51
the application shows that
blink reversed is ilam.
2:54
The original string, mali,
is missing from this text.
2:58
It's supposed to look like this.
3:01
I'm getting unexpected behavior,
but no doesn't see or
3:04
report any problems or
errors with the code.
3:08
This is the bug.
3:11
So in the next video,
3:12
will get set up to debug the application
to see where it's breaking.
3:13
Before you start, download
the project files for this workshop.
3:16
And make sure that you have
Visual Studio Code, and
3:19
no JS installed on your computer.
3:22
I've provided links in the teachers notes
with this video to help you get set up.
3:24
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