JavaScript expression to generate a 5-digit number in every case

Question

for my selenium tests I need an value provider to get a 5-digit number in every case. The problem with javascript is that the api of Math.random only supports the generation of an 0. starting float. So it has to be between 10000 and 99999.

So it would be easy if it would only generates 0.10000 and higher, but it also generates 0.01000. So this approach doesn't succeed:

Math.floor(Math.random()*100000+1)

Is it possible to generate a 5-digit number in every case (in an expression!) ?

Endothelium

Answer 1

What about:

Math.floor(Math.random()*90000) + 10000;

Qualifier

Adding the 10000 at the end does nothing. – Counterforce

Check it again, @BenBrown. Without the 10000 you can have numbers with less than 5 digits. – Qualifier

Answer 2

Yes, you can create random numbers in any given range:

var min = 10000;
var max = 99999;
var num = Math.floor(Math.random() * (max - min + 1)) + min;

Or simplified:

var num = Math.floor(Math.random() * 90000) + 10000;

Venettavenezia

Answer 3

if you want to generate say a zipcode, and don't mind leading zeros as long as it's 5 digits you can use:

(""+Math.random()).substring(2,7)

Homologous

I'm curious how the performance of this would compare to the other methods. This one appeals to me, but it seems like the string conversion and then substring could be expensive. – Cnidus

Mmm, Math.random() is not guaranteed to return at least N digits. I just tried it with firefox, (""+Math.random()).substring(2,7) can return XYZ or XYWZ which is 3/4 digits. – Stagey

I'm using it and crying – Synovia

Answer 4

What about this?

var generateRandomNDigits = (n) => {
  return Math.floor(Math.random() * (9 * (Math.pow(10, n)))) + (Math.pow(10, n));
}

generateRandomNDigits(5)

Whitelaw

Answer 5

You can get a random integer inclusive of any given min and max numbers using the following function:

function getRandomIntInclusive(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

For more examples and other use cases, checkout the Math.random MDN documentation.

Voccola