let str      = "Hello";        // String
let num      = 42;             // Number
let bool     = true;           // Boolean
let nothing  = null;           // Null
let notSet;                    // Undefined
let big      = 12345678901234n;// BigInt
let unique   = Symbol("id");   // Symbol

console.log(typeof str);   // "string"
console.log(typeof num);   // "number"
console.log(typeof bool);  // "boolean"
console.log(typeof nothing); // "object" (historical quirk)
console.log(typeof notSet);  // "undefined"
console.log(typeof big);     // "bigint"
console.log(typeof unique);  // "symbol"