hoisting(νΈμ΄μ€ν
)
- move declaration from bottom to top
- μ΄λμ μ μΈνλμ μκ΄μμ΄ νμ μ μΌ μλ‘ μ μΈμ λμ΄ μ¬λ €μ£Όλ κ²μ΄λ€.
- varμ μ μΈνκΈ°λ μ μ μ¬μ©ν μ μλ€.
μμ
console.log(age)
age = '1212312';
var age;
console.log(age)
let vs const
- Mutable -> let
- Immutable -> const
let
- ν λΉλ κ°μ λ°λΌμ κ·Έ λ³μμ νμ
μ΄ μ ν΄μ§λ€.
let text = 'hello';
console.log(typeof text);
text = 15;
console.log(typeof text);
const
- constλ κ°μ ν λΉνλ©΄ λ°λμ§μλ κ°μ΄λ€.
- favor immutable data type always
- security
- thread safety
- reduce human mistakes
const daysInWeek = 7;