Primitive data types ใน JavaScript คืออะไร?

typeof "hi";       // "string"
typeof 42;         // "number"  (both ints and floats)
typeof true;       // "boolean"
typeof undefined;  // "undefined"
typeof 10n;        // "bigint"
typeof Symbol();   // "symbol"
typeof null;       // "object"  ← famous historical bug!
typeof {};         // "object"
typeof [];         // "object"  (arrays are objects)
typeof function(){};// "function"

let a = 5; let b = a; b++;          // a is still 5 (independent copies)
let x = {n:1}; let y = x; y.n = 2;  // x.n is now 2 (same object!)