How can I get a one-digit random number in JavaScript?

Question

Possible Duplicate:
Generating random whole numbers in JavaScript in a specific range

How can I get one-digit random numbers (1, 2, 3, ..., not 0.1, 0.2, ... or 1.0, 5.0, ...) using Math.random() or some other way in JavaScript?

possible duplicates: [Generating random numbers in Javascript in a specific range?](http://stackoverflow.com/questions/1527803/), [Random between two numbers in Javascript](http://stackoverflow.com/questions/4959975), [Random number between -10 and 10 in JavaScript](http://stackoverflow.com/questions/3594177), — mellamokb, Jan 02 '13 at 13:27
Should 0 (zero) be included or not? [JohannesB's answer](https://stackoverflow.com/questions/14122894/how-can-i-get-a-one-digit-random-number-in-javascript/14123012#14123012) covers both possibilities. — Peter Mortensen, May 10 '22 at 13:30

score 27 · Accepted Answer · answered Jan 02 '13 at 13:27

27

Math.random() returns a float between 0 and 1, so just multiply it by 10 and turn it into an integer:

Math.floor(Math.random() * 10)

Or something a little shorter:

~~(Math.random() * 10)

answered Jan 02 '13 at 13:27

Blender

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nice, didn't knew about the `~~` operator – Moritz Roessler Jan 02 '13 at 13:55

score 7 · Answer 2 · edited May 10 '22 at 13:38

Disclaimer:

JavaScript's math.rand() is not cryptographically secure, meaning that this should not be used for password, PIN-code and/or gambling related random number generation. If this is your use case, please use the web crypto API instead! (W3C).

If the digit 0 is not included (1-9):

function randInt() {
    return Math.floor((Math.random()*9) + 1);
}

If the digit 0 is included (0-9):

function randIntWithZero() {
     return Math.floor((Math.random()*10));
}

score 4 · Answer 3 · answered Jan 02 '13 at 13:26

4

var randomnumber=Math.floor(Math.random()*10)

where 10 dictates that the random number will fall between 0-9.

answered Jan 02 '13 at 13:26

Paul Collingwood

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10 is not one digit, is it? – JJJ Jan 02 '13 at 13:28
lol, no, but assuming it's the fractional part the OP does not want they can work it out! Edited. – Paul Collingwood Jan 02 '13 at 13:30
1

For anyone wondering, the `Math.random()` function returns a floating-point, pseudo-random number in the range 0–1 (inclusive of 0, but not 1), so this won't return 10. – Adam Reis May 31 '18 at 08:13

Tanzeel Kazi · Answer 4 · 2013-01-02T17:31:31.103

1

Use this:

Math.floor((Math.random()*9)+1);

edited Jan 02 '13 at 17:31

answered Jan 02 '13 at 13:26

Tanzeel Kazi

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That `+ 1` removes `0` and adds `10` to the possible outputs. – Blender Jan 02 '13 at 13:30
2

The question said "digit", so I think it meant `0-9`. – Blender Jan 02 '13 at 17:29
@Blender well you are right about `10` not being a digit. I've corrected it accordingly but the OP's example did not include `0` so I think this is alright. – Tanzeel Kazi Jan 02 '13 at 17:33

score 1 · Answer 5 · answered Jan 02 '13 at 13:26

1

Math.floor((Math.random()*10));

And there goes your random integer between 0 and 10!

answered Jan 02 '13 at 13:26

gopi1410

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(Posted approx. 6 seconds after Paul Collingwood's answer.) – Peter Mortensen May 10 '22 at 13:32
"between 0 and 10" is somewhat ambiguous. Is 0 included or not? As 10 is excluded, it would suggest 0 is excluded as well. – Peter Mortensen May 10 '22 at 13:34

How can I get a one-digit random number in JavaScript?

5 Answers5

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