JavaScript, Generate a Random Number that is 9 numbers in length

Question

I'm looking for an efficient, elegant way to generate a JavaScript variable that is 9 digits in length:

Example: 323760488

Answer 1

You could generate 9 random digits and concatenate them all together.

Or, you could call random() and multiply the result by 1000000000:

Math.floor(Math.random() * 1000000000); 

Since Math.random() generates a random double precision number between 0 and 1, you will have enough digits of precision to still have randomness in your least significant place.

If you want to ensure that your number starts with a nonzero digit, try:

Math.floor(100000000 + Math.random() * 900000000); 

Or pad with zeros:

function LeftPadWithZeros(number, length) {     var str = '' + number;     while (str.length < length) {         str = '0' + str;     }      return str; } 

Or pad using this inline 'trick'.