Pretty format number using '.toLocaleString()'

// Error
console.log(123456.toLocaleString()); // wont work

// Method 1: Store it in a variable 
const n = 123456;
console.log(n.toLocaleString()); // 123,456

// Method 2: Use Number() to convert it into type Number
console.log(Number(12345).toLocaleString()); // 12,345