Introducing the Practice

[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