JavaScript#
Basics#
Data Types#
Primitive:
Number
String
Boolean
Composite:
Object
Function
Array
Trivial
Null
Undefined
Hoisting
The process whereby the interpreter appears to move the declaration of functions, variables, classes or imports to the top of their scope, prior to execution of the code.
this
#
this
refers to the object that is executing the current function.If the function that is being referenced is a regular one,
this
references the global object.If the function is a method of an object,
this
refers to the object itself.
let
, var
, const
#
Type |
Scope |
Hoisting |
Reassignment |
---|---|---|---|
|
function |
hoisted, but not initialized |
Can be reassigned and redeclared |
|
block |
hoisted, but accessing them before declaration results in a |
Can be reassigned but cannot be redeclared in same scope |
|
block |
–do– |
Cannot be reassigned or redeclared. Must be initialized at the time of declaration |
Closure#
Misc#
===
checks for both the value and the type.Local Storage vs Session Storage