⛔️ TypeError

occurs when something can't be done on the subject of the statement.

JS ⟩ error ⟩ TypeError

(runtime error) occurs when some operation can't be performed on the subject (value/object) of the statement. (that is, the subject of the action is of the "wrong" type, it isn't capable to do that kind of thing)

🔴 主題

• 'xxx' is not a function❗️

• assignment to constant variable❗️

• cannot read properties of nullish❗️

• cannot convert BigInt to Number❗️

• cannot convert Symbol to Number❗️

👥 相關

• ⛔const - can't be reassigned, redeclared❗

• ⛔ TypeError thrown if "optional chaining" not used to guard againt nullish❗

• ⛔object -> primitive conversion may result in TypeError❗

📘 手冊

• TypeError

⭐️ 重點

calling a var (as function) before initialization will cause a TypeError at runtime❗ 👉 var hoisting