es6 common leetcode topics of usage javascript

unique from arr
unique from arr and arr2 (in arr but not in arr2, in arr2, but not in arr)
unique in arr that is not in arr2


same from arr
same in arr and arr2

remove in arr that are in arr2
remove in arr that are not in arr2

filter in arr that are in arr2
filter in arr that are not in arr2

add to arr items that are in arr2 but not in arr

arr contains arr2[i]

funcs
---
toString
parseInt
math.max.apply
math.min.apply
typeof
math.abs



misc concepts
---
counter
-Infinity
pointer
is empty
obj keys
obj entries
array index
array value
ternary short-hand



loops
---
for in
for of
for i
while
break or i-- i++

conditions
---
if
then
else
unless
or
isnt
is
true
false
== | ===
null | undefined | '' | 0 | [] | {}




array
---
length
map
reduce
filter
sort
pop
indexOf
findIndex
unshift
splice
push
reverse
join
split
fill
concat
every
some
includes
swap
empty array (a = [])
spread
matrix
	for i
		for j


strings
---
includes
regexp
match
test
replace
swap
split
join



objects
---
entries
values
spread
has value
key exists
assign if key not exist
pick
omit



misc
---
new Map
new Set
new Object
new Array
Set as array
Object as Set?
Object as Map



set
---
has
add
delete
to Array
iterate



map (like obj)
---
size
get
set
has
delete
keys
values
next
iterate