✅stop using var❗️

"var" has a lot of problems, don't use it.

JS ⟩ variable ⟩ var ⟩ stop using var❗

• var is a statement❗️(side effects)

• global var / function is global object property❗️(side effect)

• accessing var before declaration gets undefined❗️(unexpected result)

• var has no block scope❗️ (unexpected result)

• var in block can't shadow outer let❗️(unexpected result)

• var can shadow parameter even in strict mode❗️(bad practice)

• var redeclaration applied even in strict mode❗️(bad practice)

👥 相關

• statement expected❗️❗

• ✅ always use strict mode

📘 手冊