🔐reserved word

keywords that can't be used as identifier. (except for property names)

JS ⟩ grammar ⟩ keywords ⟩ reserved

(keyword) that cannot be used as an identifier, except for property name❗

// ⭐️ 38 reserved words
await break case catch class const continue debugger default delete do 
else enum export extends false finally for function if import in 
instanceof new null return super switch this throw true try typeof 
var void while with yield
// ⭐️ `await`, `yield` are also contextual keywords

• replit：reserved words

🔴 主題

• reserved words

  • return

  • const

  • null

• features of reserved words

  • reserved word as property name is allowed❗️

• tools

  • str.isReservedWord - check if string is a reserved word.

⭐️ 重點

• avoid using reserved words as identifiers (at least for variable/function/label) ❗

await, yield are reserved word and contextual keywords at the same time.

👥 相關

• dot notation (.) is used to access an object's property, it's property name can be a "reserved word".

📘 手冊

• Lexical grammar ⟩ keywords ⟩ reserved words

• SyntaxError: "x" is a reserved identifier

• ECMA spec ⟩ 12.6.2 Keywords and Reserved Words ⟩ Reserved Words ⭐️

📗 參考

• TeckTutorialHub ⟩ JavaScript Keywords & Reserved Words ⭐️