Program Flow

If ... else statements
truthy and falsy expressions
comparing === to ==
The Ternary Operator
Block Scope
Loops: for, while, do...while

Conditionals Using if()

===: equal
!==: not equal

 

Truthy and Falsy

Falsy	Truthy
false 0 "" or '' (empty strings_ null undefined NaN	Everything NOT falsy 0.5 "0" String

*floating point bug in JS
use parenthesis, toFixed(...), and string to number to fix this bug 

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed

the result is true

the result is false

 

if ... else

don't forget to use braces{} 

 

Comparing === to ==

double equal sign: JS will try to convert Number to String
Triple equal sign: JS will not change its Type

True

False

 

The Ternary Operator

(Condition) ? true-statement : false-statement;

let message = (price > 10) ? 'expensive' : 'cheap';

 

Block Scope using let

Block scope: let, const

Global scope: var

 

Looping with for()

be careful to not to stuck in an infinite loop

 

Looping with while()

 

Do ... while() loop