The document outlines the evolution of JavaScript from its inception in the 1990s to the introduction of modern concepts like promises and asynchronous programming. It discusses key milestones such as the release of ECMAScript versions and the rise of technologies like Node.js and Electron. Additionally, it highlights the importance of understanding callbacks, error handling, and the advancements that have made JavaScript a versatile language for various applications.

1. JavaScript Promise
Eslam Mahmoud
http://eslam.me

2. JavaScript evolution

3. JavaScript evolution
● 90s
○ Netscape, “web needed a way to become more dynamic” Marc Andreessen 1995
○ Mocha > LiveScript > JavaScript (ECMAScript)
○ ECMAScript 2 in 1998 & ECMAScript 3 in 1999
● 2005 Jesse Garrett released a white paper coined the term Ajax (web 2.0)
● 2009 ES5 & Google Chrome and the V8 JavaScript engine
○ JavaScript as a server side language (Node.js)
● 2015 ECMAScript 6 ES6
*https://en.wikipedia.org/wiki/ECMAScript

4. Synchronous

5. Synchronous
● Step by step
● You wait for each line to
finish before moving on
● Simple

6. Synchronous

7. Asynchronous

8. Asynchronous
● Parallel execution
● Many requests can
be done
● Not blocked
waiting the other
request to get
response

9. Asynchronous

10. Synchronous Asynchronous

11. JavaScript functions
In JavaScript, functions are first-class objects
functions are of the type Object and they can be used in a first-class manner like
any other object (String, Array, Number, etc.) since they are in fact objects
themselves.
They can be “stored in variables, passed as arguments to functions, created within
functions, and returned from functions

12. Callback
Is a function that is passed to
another function as a
parameter, and the callback
function is called/executed
inside the otherFunction

13. Callback

14. You can get old
before you get
calleback

15. Handling
Errors

16. Even
more
error
handling

17. Make Sure Callback is a Function

18. Callback hell

19. Callback hell
I'm not gonna debug this

21. JavaScript Promises
The Promise object represents the
eventual completion (or failure) of an
asynchronous operation.
I Promise i will return to you when i finish

22. Promise object
● Status
○ unfulfilled, fulfilled, or failed
● Methods
○ then, catch, reject, resolve, all, race

23. Creating a Promise

24. Using
promise

25. You do not send callback to the Async function to execute it
You call Async function then execute whatever you need

26. Chaining promises

27. Chaining
promises

28. Promises with Synchronous function

29. Handling
errors

30. Is it really Asynchronous now !

31. Promise.all()

32. My life
before Promises

33. My life
after Promises

34. Whats next?
● Async
● Callback
● ES6
● Promises
● Await, yield, generator
● JavaScript As backend (Node.js)
● JavaScript For desktop (electron)
● JavaScript for mobile (phonegap)
Where to go?

35. Showcase
● JavaScript For desktop (electron)
● JavaScript As backend (Node.js)

39. ref
● https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_O
bjects/Promise
● https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promis
es
● https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators
/await
● http://es6-features.org
● https://nodejs.org
● https://electron.atom.io
● https://insights.stackoverflow.com/survey/2016

40. ? || //