Primitif vs Objek & Tipe Inti

Pengantar

Tujuh primitif: tur typeof

// Seven primitives and typeof
const n = 42;                 
// number
const bi = 42n;               
// bigint
const s = "hello";            
// string
const b = true;               
// boolean
const u = undefined;          
// undefined
const nl = null;              
// null (primitive)
const sy = Symbol("id");      
// symbol (unique each time)

console.log(typeof n, typeof bi, typeof s, typeof b);
console.log(typeof u, typeof nl, typeof sy);
// Note: typeof null is "object" (historical quirk)

Primitif vs objek

Perangkap objek wrapper

// Avoid wrapper constructors for primitives
const s1 = "hi";              
// primitive string
const s2 = new String("hi");  
// String object (wrapper)

console.log(typeof s1);       
// "string"
console.log(typeof s2);       
// "object"

console.log(s1 === "hi");     
// true (value compare)
console.log(s2 === "hi");     
// false (object vs primitive)

Dasar BigInt & Symbol

// BigInt: integers beyond Number.MAX_SAFE_INTEGER
const big = 9007199254740993n;  
// 2^53 + 1
console.log(big + 7n);

// Symbol: unique identifiers
const a = Symbol("token");
const b = Symbol("token");
console.log(a === b); 
// false — symbols are always unique

null vs undefined

Kuis typeof null

Ringkasan