back js...
01 - variable
02 - type data
03 - operator aritmatika
04 - console.html
05 - string template
06 - konversi string
07 - type data array
08 - type data object
09 - percabangan
10 - pop up
11 - undefined
12 - null
13 - switch
14 - typeof
15 - in operator
16 - ternary operator
17 - nullish coalescing
18 - optional chaining
19 - falsy dan truthy
20 - operator logika