⤴️return

🚧 施工中

JS ⟩ statement ⟩ control flow ⟩ jump ⟩ return

(statement)

end execution and return a value to the caller. undefined is returned if expr omitted.

return <expr>

🧨 雷區

return statement can be used only within the body of a function, using it anywhere else causes a SyntaxError.

return is affected by automatic semicolon insertion❗

⚠️ 注意：用 return 時，不要寫成這樣：

return
    a + b;

❌ 這種寫法 return 後面會被自動加上 ";" 分號❗

return;        // 自動加上「;」分號❗️ 
a + b;

✅ 建議寫成這樣：

return (
    a + b
);

⭐️ 重點

when the { ... } of an arrow function are omitted, a return value is sent out without using return.

if the code you need to wrap a scope around has return, this, break, or continue in it, don't use a function/IIFE(which has its own function boundary), use a block instead❗️

📗 You Don't Know JS Yet: Scopes & Closrues

👥 相關

• return is a reserved word.

📘 手冊

• Statements and declarations ⟩ control flow ⟩ return

🚧

• function caller

• undefined