📘function declaration instantiation

🚧 under construction

JS ⟩ value ⟩ function ⟩ declaration ⟩ instantiation

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⭐️ 重點

⭐ function declaration instantiation

When an execution context is established for evaluating a function：

• a new Function Environment Record is created.

• bindings for each parameter are instantiated in that Environment Record.

• body declarations are also instantiated：

  • ⭐ if the parameters do not include any default value initializers： the body declarations are instantiated in the same Environment Record as the parameters❗(👉 parameter scope)

  • ⭐ if default value initializers exist：

    a second Environment Record is created for the body declarations❗

• parameter(s) / function(s) are initialized as part of FunctionDeclarationInstantiation. All other bindings are initialized during evaluation of the function body.

📘 JS spec ⟩ FunctionDeclarationInstantiation

👥 相關

• redeclaration

• variable redeclaration

• simple vs. non-simple parameter - determines whether parameters and body declarations are stored in the same environment record.

• parameter scope - the scope where all the parameters live.

• execution context ⟩ environment record

📘 手冊

• JS spec ⟩ FunctionDeclarationInstantiation

📗 參考

• YDKJS: Scope & Closures (v.2) ⟩ Appendix A

❓

Q：

• does "evaluating a function" mean "calling a function"❓

• or, it means "evaluating the function itself" (to be a "function" object)❓

execution context 是 runtime 的才有的動作，但 evaluating the function to be a "function" object 是 compile-time 的問題，所以我猜答案應該是第一個吧❓

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• binding

• default value initializer

• function environment record