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!) ?

score 201 · Accepted Answer · answered Feb 01 '10 at 08:51

201

What about:

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

answered Feb 01 '10 at 08:51

Rubens Farias

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Adding the 10000 at the end does nothing. – Ben Brown Dec 18 '17 at 13:18
13

Check it again, @BenBrown. Without the 10000 you can have numbers with less than 5 digits. – Rubens Farias Dec 18 '17 at 14:33

score 62 · Answer 2 · answered Feb 01 '10 at 08:49

62

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;

answered Feb 01 '10 at 08:49

Guffa

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1,005

score 25 · Answer 3 · answered Feb 01 '10 at 11:58

25

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)

answered Feb 01 '10 at 11:58

miaubiz

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5
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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. – Danation Oct 15 '13 at 19:44
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. – Daniele Santi Dec 09 '15 at 15:30
2

I'm using it and crying – Alex Shtromberg Sep 25 '19 at 14:58

score 6 · Answer 4 · answered Jul 16 '20 at 20:36

6

What about this?

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

generateRandomNDigits(5)

answered Jul 16 '20 at 20:36

SanS

1,137
9
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score 1 · Answer 5 · answered Aug 04 '16 at 23:20

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.

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

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