The document summarizes a presentation about JavaScript fundamentals. It discusses the history and origins of JavaScript, key concepts like functions, this, closures, and array methods. It also outlines new features introduced in ES5 and ES6 like strict mode, map/filter/reduce, arrow functions, and array.from. The presentation aims to cover fundamental JavaScript concepts and features that developers may wish they knew.

1. PeopleSpace 23 August 2016
The JavaScript You Wished
You Knew

2. Troy Miles
Troy Miles
Speaker and author
https://
therockncoder.com/
rockncoder@gmail.com
@therockncoder

3. @therockncoder
Please follow me on twitter

4. Have MEAN October
October 15th & 16th
MongoDB, Express.js, Angular, and Node
Build a full stack site using the latest versions
Only $195
http://peoplespace.us/javascript/

5. Resources
http://www.slideshare.net/rockncoder/the-javascript-
you-wished-you-knew
https://github.com/Rockncoder/JSFoundations

6. Agenda
The big lie
What is this?
function, function, function
call, apply, and bind
high order functions
closure
splice vs slice
strict mode
map, filter, and reduce
arrow functions
array.from
Summary

7. The big lie
Brendan Eich was hired to create Scheme for the
browser
It was released in Sept. 1995 as LiveScript
It was renamed JavaScript in Dec. 1995
At the time NetScape and Sun were partners
Sun owned the trademark, JavaScript

8. (What is Scheme?)
Scheme is a functional language in the LISP family
Some of the features of JavaScript like high order
functions and closures come from its Scheme mother

9. Bad math
JavaScript doesn’t have multiple kinds of numbers
This means we are vulnerable to some shortcomings of
base-2 numbers

10. What is this?
this is a keyword
You can’t directly modify it
It is the context in which the code is running
(It was the dumbest possible name for a keyword)

11. function, function, function

12. The secret parameters
Every function receives two secret parameters
this - which points to the current context
arguments - an array-like structure holding all of the
passed parameters

13. Every function returns a
value
If a function lacks a return statement, the function
returns “undefined”
undefined is a primitive type in JavaScript
It can be used to compare in strict equalities
Better to use typeof since it won’t throw an error

14. 4 ways to invoke a function
1. As a function
2. As a method of an object
3. As a function constructor
4. Using call or apply

15. call, apply
call and apply are very similar
both allow you to set both of the secret parameters
call accepts a list of parameters for the arguments
apply takes an array for the arguments
Remember: A is for array, arguments, & apply

16. bind
Bind is weird
It creates a new function based on an older one
It permanently assigns a this to the new function
Remember: it binds this to the the function

17. high order functions
Functions are first class objects in JavaScript
Any place you use a variable, you can substitute with a
function
You can pass functions to functions
And return functions from functions

18. What is a closure?
A closure is a function which remembers the
environment in which it was created
This is super-powerful and enables JavaScript to do
things not possible in other language

19. ES3

20. splice vs. slice
Both introduced in ES3(1999)
The splice() method changes the content of an array by
removing existing elements and/or adding new
elements.
The slice() method returns a shallow copy of a portion
of an array into a new array object.
splice is DESTRUCTIVE

21. arguments
arguments is array-like since it has a length property
but it is not an array because it doesn’t have any of the
array methods
to convert it to an array is easy

22. ES5

23. strict mode
“use strict”; or ‘use strict’;
Must be the first statement in a file or function
Turns on “ES5” mode
JavaScript becomes more strict

24. map, filter, reduce
map - transform one array into another
filter - checks every value of an array, creating a new
array
reduce - turns an array into a scalar value

25. array methods
most array methods are passed the same three
parameters, in the same order
element - the current value
index - the current array index
array - the entire array

26. ES6 / ES2015

27. array.from
Creates a new array from array like objects or iterators
Can turn arguments, strings, and others into arrays
Can generate arrays based on values passed in

28. arrow function
a short form of the anonymous function
Captures the this of its parent code
Best for non-method code
In short form, it does an implicit return
In long form, you must include a return statement

29. Resources
http://www.slideshare.net/rockncoder/the-javascript-
you-wished-you-knew
https://github.com/Rockncoder/JSFoundations

30. The End