🔰scope

🚧 under construction

JS ⟩ scope

( visibility of variable)

the current context of execution in which values and expressions are "visible" or can be referenced.

🔴 主題

• concepts about scopes

  • context vs. scope

  • lexical environment vs. scope

  • scope chain

  • lexical scope / dynamic scope / static vs. dynamic scoping

  • lexical environment - stores local variables/functions/this.

• kindes of scopes

  • top-level scope - the scope of a JS file.

  • global scope： default scope for all code running in script mode.

  • module scope： scope for code running in module mode.

  • function scope： scope created with a function.

  • block scope：scope created with a pair of curly braces. (where let / const can belong to)

• special scopes

  • function name scope - where name of function expression lives in.

  • parameter scope

  • "for-init" scope - where the for loop initialization variables live in.

• hoisting

  • function hoisting

  • var hoisting

  • function expression not hoisted

• other topics

  • modify current scope at runtime❗️

  • eval has its own scope in strict mode

⭐️ 重點

👥 相關

📗 參考

📘 手冊

🗣 討論