console.log(Math.floor(100000 + Math.random() * 900000));
Will always create a number of 6 digits and it ensures the first digit will never be 0. The code in your question will create a number of less than 6 digits.
console.log(Math.floor(100000 + Math.random() * 900000));
Will always create a number of 6 digits and it ensures the first digit will never be 0. The code in your question will create a number of less than 6 digits.