🈯variable declaration

• JS ⟩ declaration ⟩ variable

• JS ⟩ variable ⟩ declaration

(declaration) declares a var / let / const variable.

⭐️ 重點

function (declaration) vs. variable declarations

• function declaration is instantly fully initialized.

• variable declarations is undefined/uninitialized initially.

👉 hoisting

📗 JS.info ⟩ Function Declarations

(❗redeclaration ) JS is lenient with var, strict with let.

• var redeclaration applied even in strict mode❗️, even in strict mode❗

• let redeclaration not allowed even in sloppy mode❗️, even in sloppy mode❗

there is no type associated with variable declarations❗

🔴 主題

• variable declarations

  • var / let / const

  • initial value

  • redeclaration

👥 相關

• function declaration

• hoisting / var hoisting

📘 手冊

• Grammar and types ⟩ variable declarations