scope | web.dev

concepts about scopes
- context vs. scope
- lexical environment vs. scope
- / /
- - stores local variables/functions/this.
kindes of scopes
- - the scope of a JS file.
- ： default scope for all code running in script mode.
special scopes
- - where name of function expression lives in.
other topics

scopes are

determined at compile-time.
but () created at , each time a scope is entered.
but in , you can modify scope (I think the term "scope" is not quite accurate, maybe ❓) at . ( 👉 ❗)

The scope of a code block can reach all its parents so it can use its parent’s variables. In this way, we have a , chain of all parent’s scope.

vs.

scope：visibility of .

vs.

： relative to each JS file.

in , each JS file is treated as a .

inner scopes have access to outer scopes, but not vice versa.

a (or ) can be used to create a scope to hide s/ s.

if the code you need to wrap a around has , , , or in it, don't use a /(which has its own ), use a instead❗️

📗

雖說似乎有一個奇怪的，但裡面變數的表現其實更像是。👉 ⟩

scopes are determined at compile-time.
scopes are created at runtime.
in strict mode, script in eval has its own scope.
... 🚧

Scope