⤴️try-catch-finally

🚧 under construction

• JS ⟩ statement ⟩ control flow ⟩ jump ⟩ try-catch-finally

• JS ⟩ error ⟩ handling ⟩ try-catch-finally

(statement)

try { ... }            // run code that may throw.
catch (err) { ... }    // error handling (and∨ rethrow)
finally { ... }        // cleanup code

🧨 雷區

一但使用 try，一定要用 catch(err) 去抓「所有的錯誤」，否則可能會漏掉「自己沒有預期的錯誤」❗

try {
  noSuchFunc();  // ⛔ ReferenceError (not catched)
} catch(err) { 
  // `console.log(err)` omitted ... (dangerous)❗
  // or, `throw err` omitted ...
}
// the code will continue executing happily❗

⭐️ 重點

if a finally clause issues a return statement, the method returns normally, even if an exception has been thrown and has not yet been handled.

bare catch clause

in ES2019 and later, the parentheses / (error) identifier in the catch clause can be omitted.

👥 相關

• error handling

• throw

📗 參考

• JavaScript: The Definitive Guide ⟩ 5.5.7 try/catch/finally

📘 手冊

• try...catch