Starting to Learn Javascript

KEYWORDS

100

DECLARES A VARIABLE THAT CAN BE REASSIGNED A NEW VALUE LATER.

let

200

DECLARES A VARIABLE THAT CANNOT BE REASSIGNED A NEW VALUE ONCE IT HAS BEEN ASSIGNED.

const

300

WHEN A FUNCTION ENCOUNTERS THIS KEYWORD, IT IMMEDIATELY EXISTS THE FUNCTION AND GIVES YOU THE VALUE SPECIFIED AFTER THIS KEYWORD.

return

400

THIS TWO LETTER KEYWORD IS USED AT THE START OF A CONDITIONAL STATEMENT. WHEN TRUE IT EXECUTES THE BLOCK OF CODE 

if

500

USED TO DEFINE REUSABLE BLOCKS OF CODE THAT CAN BE EXECUTED BY INVOKING (CALLING) ITS NAME FOLLOWED BY PARENTHESIS

 function 

OPERATORS

100

USED FOR SUBTRACTION

- 

(minus sign) 

200

USED FOR MULTIPLICATION

*

(start, asterisk)

300

CHECKS IF TWO VALUES ARE STRONGLY EQUAL

===

(TRIPPLE EQUALS) 

400

ASSIGNS A VALUE TO A VARIABLE

= (single equals) 

500

USED TO RETURN THE OPPOSITE BOOLEAN VALUE

! (not operator) 

DATA TYPES

100

REPRESENTS NUMERIC VALUES EITHER AS INTEGERS OR FLOATING-POINT (DECIMALS)

number

200

REPRESENTS EITHER "TRUE" OR "FALSE"

boolean

300

REPRESENTS A SEQUENCE OF CHARACTERS AND CAN BE DEFINED USING SINGLE QUOTES, DOUBLE QUOTES, OR BACKTICKS

string

400

THIS 9 LETTER WORD IS A SPECIAL VALUE THAT INDICATES THE ABSENCE OF AN ASSIGNED VALUE OR AN UNINITIALIZED VARIABLE.

undefined

500

THIS 3 LETTER WORD REPRESENTS THE INTENTIONAL ABSENCE OF A VALUE

null

NOT JAVASCRIPT

100

SHORT FOR CASCADING STYLE SHEETS, THIS TYPE OF FILE EFFECTS HOW THE PAGE LOOKS

CSS

200

SHORT FOR HYPERTEXT MARKUP LANGUAGE, THIS IS THE STANDARD MARKUP LANGUAGE FOR DOCUMENTS TO BE DISPLAYED IN THE WEB BROWSER.

HTML

300

THIS HTML ATTRIBUTE SPECIFIES THE JAVASCRIPT CODE OR ACTION TO BE EXECUTED WHEN THE BUTTON IS CLICKED.

onclick

400

THE APPSTORE FOR JAVASCRIPT PROGRAMS, USES NODE TO DOWNLOAD JAVASCRIPT LIBRARIES. CAN BE ABBREVIATED  TO 3 LETTERS 

NODE PACKAGE MANAGER (NPM)

500

POPULAR CODE EDITOR FROM MICROSOFT FOR WRITING AND EDITING CODE LIKE HTML, CSS, OR JS. IT EVEN ALLOWS YOU TO CHANGE THE THEME.

Visual Studio Code

WHAT IF?

100

const a = 7;
const b = 10;

if (a != 77) { 
  console.log("FIRST CASE") 
}

FIRST CASE

200

const a = 7;
const b = 10;

if (a == 7) {   
  console.log("FIRST CASE") 
}
if (b == 10) { 
  console.log("SECOND CASE") 
}

FIRST CASE 
SECOND CASE 

300

const a = 7;
const b = 10;

if (a == 7) { 
  console.log("FIRST CASE") 
}
else if (b == 10) { 
  console.log("SECOND CASE") 
}

FIRST CASE

400

const a = 7;
const b = 10;

if (a >= 7) { 
  console.log("FIRST CASE") 
}

if (a <= 7) { 
  console.log("SECOND CASE")
}

FIRST CASE 

SECOND CASE

500

const a = 7;
const b = 10;

if (a == 7) { 
  console.log("FIRST CASE") 
}
if ( a < b ) { 
  console.log("SECOND CASE") 
}
else if (b == 10) { 
  console.log("THIRD CASE") 
}

FIRST CASE
SECOND CASE