This document provides an overview and agenda for a session on JavaScript basics. It introduces concepts like hoisting, differences between var, let and const, arrow functions, recursion, arguments.callee, memoization, and promises. It also briefly discusses the history of JavaScript, from its creation in 1995 and renaming to JavaScript in 1996 to the introduction of EcmaScript to standardize the language. The agenda outlines explanations and demonstrations of these JavaScript fundamentals concepts.

1. Path to Code
Begin Your Salesforce Coding Adventure

2. Episode 15
Basics of JavaScript

3. Jitendra Zaa
Salesforce MVP
Sr Technical Architect
23x Certified
@Jitendra Zaa
Speaker

4. Some House Rules
• Please mute your mic
• Keep adding questions in Zoom Q&A Window
• No question is too small
• Questions will be answered in last 15 mins

5. Agenda
• Introduction to JavaScript
• Hoisting
• var vs let vs const
• Different ways to write functions
• Arrow Functions
• Recursion
• Arguments.Callee
• Memoization
• Promises

6. History of JavaScript

7. 1995
• Mocha created by Brendan Eich in 10 days
• Renamed to LiveScript Officially
• To piggyback popularity of Java, renamed to JavaScript
• Worried about Java Trademark, Microsoft released its own version
of JavaScript as JScript

8. 1996
• Worried about future and standardization , Ecma group was
introduced to decide feature and capabilities of language
• EcmaScript was trademarked by Ecma group to define the standard
of JavaScript

10. Basics of JavaScript

11. Hoisting

12. Hoisting
The process of assigning variable declarations a default value of
undefined during the creation phase is called Hoisting.

13. Demo 1
Hoisting

14. Var
Var :
function scoped
undefined when accessing a variable before it’s declared

15. let
let :
block scoped
ReferenceError when accessing a variable before it’s declared

16. const
const :
block scoped
ReferenceError when accessing a variable before it’s declared
Can’t be reassigned

17. Demo 2
Different ways to write functions

18. Demo 3
Sequence of Method matters ?

19. Demo 4
Recursion

20. Demo 5
Arguments.Callee

21. Arrow Functions

22. Arrow Function
var multiplyES5 = function(x, y) {
return x * y;
};
const multiplyES6 = (x, y) =>
{ return x * y };

23. Memoization
Memoization is programming practice in which returned results from
functions are saved in cache, thus boosting the performance of long
running / iterative methods.

24. Demo 6
Memoization and Arrow Methods

25. Promises
Are Asynchronous
Has three states
1. Pending
2. Fulfilled
3. Rejected

26. Reference
• Secrets of Javascript by John Resig
• Hoisting
• Arrow Functions

27. Q&A

28. Next Episode 16
Getting Started with Lightning Web Components

29. Thanks