Hello class
Javascript is also called "ECMA script"
When JavaScript was created, it initially had another name: “LiveScript”.
Javascript is commonly used for making the website 'alive'
Lynx is another way to see the content of website but rather using GUI it based on TEXT
how to use Lynx: lynx website_name, to quit Lynx you can press 'q' and press 'y' (if asked)
most of website that require interaction it's commonly using javascript
to switch to virtual-terminal you can press ctr+alt+[f1~f6]
to switch back to GUI mode you can press ctr+alt+f7
How webs flow work:
Browser -> WebServer -> Browser
Front-end is how the user programm their web-design
Back-end is how the programmer programm their website-system, mean hows the web supposed to work
Basically web-browser sending request to the web-server then the web-server will send the answer based on what the web-browser requested and the browser will display it as .html format
For back-end development the most commonly used languages are php and asp.
"php" is from open sourcing
"asp" is from Microsoft
node.js is basically javascript on the back-end side
Nodejs executes JS outside a web-browser
nodejs:
alert<=(similar to console.log)
esc+a,e,b;backspace
camelCase-are upper case letters
reserved keywords-you can't use to name var
const-(similar to let, but value can't be changed)
JS number range: 2^53-1 to -2^53-1
BigInt-integers of arbitrary length(out of the range)
Simple quotes:
double quotes: "Hello"
single quotes: 'Hello'
Extended functionality:
backticks: Hello
typeof x - operator
typeof(x) - function
"empty" values = 0;null;undefined;NaN
(in boolean they're treated as FALSE)
Node.js is an open-source, cross-platform, back-end JavaScript runtime environment that runs on the V8 engine and executes JavaScript code outside a web browser.
In single if statement it will be treated as boolean, an empty string will treated as false and vice versa
VIM shortcuts/cheatsheet:
esc-visual mode
i-insert mode
:q-quit
:q!-forced quit
:w-save
:wq-save and exit
h,j,k,l-arrows
((code beautifier)https://beautifier.io/)
Precedence, Operator, Operand, Expression Tree, Expression, Strict Equality, Short-Cicruit evaluation, Lexical-Scoping
Most operator are left associative
Primitive data types - boolean, byte, char, short, int, long, float and double
Reference data types - Array and Object
Exponentiation
Code obfuscation
The ternary operator "?:" works like an "if" statement
Function_Defination_Invocation
^Right associative (**)
^short circuit evaluation - is the another feature of OR
^(Let) - has a function called "lexical scoping".
^
left associative (-(+)
a=b=c=2+2 -"this is exponentiation tree"
y=x++; -"Code obfuscation"
== regular equality check
=== strict equality check
:ternary operator - has three operands
eg. y= x>5?3:7 (>, ?, ;)
:let is a newer(than var, which is tricky and confusing) way to define a variable
&& ||
"short circuit evaluation" - So when Java finds the value on the left side of an && operator to be false, then Java gives up and declares the entire expression to be false. That's called short circuit expression evaluation.
Shallow copy - points to the reference address of the original collection structure (object or array) which holds the value in the new variable
Deep copy - creates a duplicate of all the properties of the source object into the target object
definition
invocation
"callback function" - is a function passed into another function as an argument to be executed later. When you pass a callback function into another function, you just pass the reference of the function, the function name without the parentheses.
Keyword:
Pretty_printing_javascript, padding_number_javascript, Destructive, Un-destructive, Concatenation
destructive (modification in place)
non-destructive (returns a new copy)
Destructive:
pop();
push();
shift();
unshift();
splice()
Non-destructive:
concat();
filter();
map();
slice()
concatention - in JavaScript, we can assign strings to a variable and use concatenation to combine the variable to another string. To concatenate a string, you add a plus sign+ between the strings or string variables you want to connect.
concatenation - putting two things end-to-end/join two or more strings =>.concat([''])
nested array - has one or many arrays as the element of an array (arrays inside an array)
json.stringify - converts a deeply nested object or value into a string
Null string
CSV - an open file format for spreadsheet
Nested Array
[] - ordinary
{} - associative array
object (only in JS) = Phyton Dictionary,Associative arrays,map , hash table
for…in :used in dictionary and object
for…of :used in ordinary array indexed by 0, 1, 3…
LINTER tells your mistakes
tar cvzf => create
tar tvzf => table of content
tar xvzf => extract
meta data
content delivery network(CDN) - jQuery library
It's ok to ask for classmates' help and even look at some small pieces of their code, but it is not ok to take a screenshot or even copy files directly.
jquery "$.get" example
papaparse (search for cdn)
datatables examples "Javascript sourced data"
plotly javascript getting started
plotly javascript scatter plot example
https://plotly.com/javascript/marker-style/
https://cdn.datatables.net/plug-ins/1.10.25/sorting/natural.js(treat as numbers)
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