Introduction to JavaScript, Thinkful LA June 2017

1. June 2017
Intro to JavaScript
WIFI: Cross Campus Events
bit.ly/intro-js-la

2. About us
We train developers and data
scientists through 1-on-1
mentorship and career prep

3. About me
• Brendan Barr
• Full-stack JavaScript developer
• LA-based Thinkful mentor

4. About you
• What are your programming goals?
• I’d like to become a developer
• I have an idea I’d like to build
• I’d like to work better with developer
• What is your programming experience?
• First lines of code will be written tonight!
• Been self-teaching for 1-3 months
• Been at this for longer than 3 months

5. Format for tonight
• Basics of how the web works
• Background about Javascript
• Review key Javascript concepts
• Practice with some challenges
• Next steps to continue learning

6. Before we get started…
• Chrome Developer Tools provides an
interactive JavaScript console, where you
can run and debug code:
• View -> Developer -> JavaScript console
• Shortcut: option-command-J on a Mac;
Ctrl + Shift + J on a PC
• Type the following command and hit enter:
alert(“Hello world!”);
• Type: 2+2;

7. What is programming?
Programming is writing instructions for a computer to
execute. Programming is problem-solving.

8. How the web works
Type a URL from a client (e.g. facebook.com)
Browser communicates with DNS server to
find IP address
Browser sends an HTTP request asking
for specific files
Browser receives those files and renders
them as a website

9. Clients / Servers
Client (sends requests)
Frontend Developer
Manages what user sees
Server (sends response)
Backend Developer
Manage what app does

10. Example: facebook.com
HTML, CSS, &
Javascript render
interactive newsfeed
Algorithm determines
what’s in your feed
Request
Get data about your
friends’s and their posts
Open browser
and navigate to
facebook.com
Application Logic
Database
Response
Client Server

11. Brief history of Javascript
• Written by Brendan Eich in 1995 for Netscape
• Initial version written in 10 days
• Completely unrelated to Java, named as a
marketing stunt because Java was “hot” at the
time
• Continues to evolve under guidance of ECMA
International, driven by browser makers

12. Javascript today
JavaScript is the most commonly used programming language on earth. Even Back-
End developers are more likely to use it than any other language.

13. This makes it a good place to start
• Has large community of developers, libraries and
frameworks
• Lots of job opportunities
• Also the syntax is easier to understand for first-time
developers

14. Are we learning frontend or backend?
100% of client-side web development is in Javascript.
You can also use Javascript to write server-side code
thanks to Node.js. So technically both!

15. Concepts we’ll cover
• Variables
• Data types: strings, numbers, booleans
• Functions

16. Note on where to write you code
When working as a programmer, you’ll use a text editor
or an “Integrated Development Environment” (IDE).
Tonight we’re using JSBin so we can skip setup, see
results immediately and easily share code

17. Javascript variables
• A variable is a name that is attached to a value — it gives
us a shorthand way to refer to the value elsewhere
• Helps us remember things while we’re executing a
program: “managing state”
• Example on JSBin: http://bit.ly/js-example-one

18. Examples
• Declaring variable: var firstVariable;
• Assigning value: firstVariable = 6;
• Retrieve value: alert(firstVariable)
Example on JSBin: http://bit.ly/js-example-two

19. Best practices for naming variables
• Names should be (extra) descriptive: “numberOfCats”
is better than “x”
• Use camelCasing where first word starts with lower
case, subsequent words are upper case
• Must start variable names with a letter

20. What values can be assigned to a variable?
• String
• Number
• Boolean
• Also Null, Undefined, Arrays, and Objects

21. Introducing strings
We use strings a lot. Strings are created with opening
and closing quotes (either single or double):
var foo = ‘bar’;
var bar = “foo”;

22. Combining (or “concatenating”) strings
Javascript lets you combine two strings by using the +
operator. Let’s try it in the console!
var host = “Thinkful”;
var className = “Intro to Javascript”;
console.log(className + “ with “ + host);
=> Intro to Javascript with Thinkful

23. Quick challenge
• Open JSBin in your browser
• Store your first name in one variable
• Store your last name in another variable
• Combine the two and log your full name

24. Introducing numbers
The number type in Javascript is used to represent all
kinds of numbers, including integers and decimals.
var integerNumber = 3;
var floatingPointNumber = 3.00;

25. Quick challenge
• Open JSBin
• Store two numbers in two different variables
• Add the two numbers
• Multiply the two numbers

26. Introducing booleans
Boolean is just a fancy word for “true” or “false”
var loggedIn = true;
if (loggedIn == true) {
alert(“loggedIn was set to true!”)
}

27. Basic functions
A function lets you separate your code into bite-sized
pieces which you can use over again.
When you write a function to use later, you are
“declaring” it. When you use (or run) that function you
are “calling” it.

28. Example
Declaring a function
function doSomething () {
alert(“Done!”)
}
Calling a function
doSomething()

29. More about basic functions
• Functions can save us time because we can use them
over and over code. They are like building blocks.
• Functions make your code more organized and easier
to read
• Javascript has many built-in functions — you’ve already
used a couple!
• In writing less trivial programs, you’ll write many, many
functions

30. Challenge #1
• Go to JSBin.com, make sure auto-run with Javascript
isn’t selected
• Declare and call this function:
• function myFirstFunction() {
console.log(“Hello World!”);
• }
• myFirstFunction();
• Click “Run with JS” to see output in console

31. Challenge #2
• Open JSBin
• Write a function that logs your name
• Write a function that adds two numbers and logs the
result
• Call both functions

32. More advanced functions — parameters and return
• We can “give” a function some values to use. We call
the values we send into a function “parameters”
• We can have a function give a single value back. We
use a “return” statement to do that.
• We define what parameters the function accepts when
we declare the function.
• We send the actual parameters when we call the
function — we put those parameters in the
parentheses. Example: addTwoNumbers(2, 3);

33. An example
function addTwoNumbers(numberOne, numberTwo) {
return numberOne + numberTwo;
}
var result = addTwoNumbers(2, 3);
alert(result);

34. Challenge
• Open JSBin
• Write a function that takes your first name and your
last name as two parameters
• Return a string with your full name
• Call that function

35. Learning to learn
• Google is your friend!
• Practice at the edge of your abilities
• Ignore the hot new thing. Instead go deep with one
technology

36. Ways to keep learningLevelofsupport
Structure efficiency

37. 1-on-1 mentorship enables flexibility
325+ mentors with an average of 10
years of experience in the field

38. Support ‘round the clock

39. Our results
Job Titles after GraduationMonths until Employed

40. Try us out!
• Initial 2-week trial
includes six mentor
sessions for $50
• Learn HTML/CSS and
JavaScript
• Option to continue
onto web
development
bootcamp
• Talk to me (or email
noel@thinkful.com) if
you’re interested

41. October 2015
Questions?
noel@thinkful.com
schedule a call through thinkful.com