Preview
Video Player
00:00
00:00
Introducing the Practice
4:04Practice working with let and const variables in JavaScript.
[MUSIC]
0:00
Hey there.
0:09
Ashley here.
0:10
Today we're going to be
Practicing Working With Const and
0:11
Let Variables in JavaScript.
0:14
This is a follow up to the first part of
the Getting Started With ES 2015 Course.
0:16
Defining variables with let and const.
0:21
If you haven't finished that section yet
or are unfamiliar with const and
0:24
let variables, now might be a good
time to go and review those videos.
0:28
I've included a link to them
in the teacher's notes.
0:32
In this practice session,
0:35
you'll be writing a function,
editing a function, and
0:36
changing some other code to help you get a
feel for how const and let variables work.
0:39
And how they're different from
variables declared with a var keyword?
0:44
There's a workspace attached to this
video that includes the file you'll
0:48
be working out of with some
more detailed instructions.
0:51
You'll use the workspace console and
node to run your code.
0:54
Node, if you haven't used that before
is a way to run JavaScript code
0:58
outside of your browser.
1:02
This workspace is all set up to use node.
1:03
So when you're ready to run your file,
open up the work space console,
1:06
type node followed by a space and
then the name of your file.
1:10
In this case, let_const.js then hit Enter.
1:16
There's a note on how to do this
in the instructions as well.
1:22
Go ahead and
open up the let_const.js file.
1:25
Inside you'll see here instructions
written as JavaScript comments
1:29
at the top of the file.
1:33
After these instructions,
you'll see three variable declarations.
1:35
The first is teachers,
an array containing one object.
1:39
Object should be familiar to you from
the JavaScript Loops, Arrays and
1:43
Objects course.
1:47
The second variable
declaration is courses.
1:49
An array containing six
JavaScript course titles.
1:52
Finally, we've declared i.
1:57
A variable that's equal to
the length of the courses array.
1:59
After these variable declarations, you'll
see a function called add new teachers.
2:04
That takes one parameter, newTeachers.
2:09
But whoops, something's missing here.
2:12
Our addNewTeachers function doesn't
have any code inside of it.
2:15
Your first goal is to complete this
function by writing some code that lets us
2:18
add new teachers to our teachers array.
2:22
After the addNewTeachers function,
2:25
you'll see a function called
printTreehouseSummary.
2:27
This function runs but it's outputting an
incorrect number of treehouse, teachers,
2:30
and courses.
2:34
Use what you know about let and const
in JavaScript to fix this function so
2:36
it logs the correct
numbers to the console.
2:41
Now don't worry if the string format used
in the console.logs are unfamiliar to you.
2:44
I'm using something called template
literals which offer a more concise and
2:49
simple way to display
string data in ES2015.
2:53
You'll learn all about template
literals in the next segment of
2:56
the Getting Started With ES2015 Course.
2:59
If you are to run your code at this point,
you would get an error message.
3:03
Your final goal for
3:07
this practice session is to figure out
what's causing the error and fix it.
3:08
The error message in the consul should
give you some clues about where to start
3:12
and if you're really stuck check
the teacher's notes for a hint.
3:15
Once you've completed this three tasks
you should be able to run your code.
3:19
Now remember to run your code you're gonna
type node, then the name of the file,
3:24
which is let_const.js and then hit Enter.
3:28
Now if your code works correctly,
your output should look just like this.
3:33
If you think you're ready to get started
go ahead and try to program your solution.
3:38
If you're having trouble,
that's 100% okay.
3:43
Practicing, trying new things,
and playing around with code,
3:46
is part of how we learn, and
is a vital part of programming.
3:49
Either way, come back and watch video two
to check your work and see my solution.
3:53
If you're looking for
some more background info,
3:57
don't forget to check the teacher's
notes for links to related coursework.
4:00
See you soon.
4:03