javascript - Regular Expression - How can I match all numbers less than or equal to Twenty Four? - Stack Overflow

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I'm somewhat new to regular expressions and am writing validation for a quantity field where regular expressions need to be used.

How can I match all numbers less than or equal to 24?

I tried

var pat = /^[1-9]$|^[1-2]\d$|^3[0-6]$/;

But that only matches 1-24. Is there a simple way to match all possible numbers less than or equal to 24?

I'm somewhat new to regular expressions and am writing validation for a quantity field where regular expressions need to be used.

How can I match all numbers less than or equal to 24?

I tried

var pat = /^[1-9]$|^[1-2]\d$|^3[0-6]$/;

But that only matches 1-24. Is there a simple way to match all possible numbers less than or equal to 24?

• javascript
• regex

Share Improve this question Follow edited Jan 13, 2016 at 5:20 Tushar 87.3k2121 gold badges163163 silver badges181181 bronze badges asked Jan 13, 2016 at 4:43 Gobinath MGobinath M 2,03166 gold badges2929 silver badges4747 bronze badges 6

• 2 Do yo want to match negative numbers too? – Tushar Commented Jan 13, 2016 at 4:49
• is the quantity field not numeric? function Number might help. – Jorg Commented Jan 13, 2016 at 4:51
• Your regex actually matches 1-36 . . . but anyway, you need to describe your rules much more precisely than just "all numbers less than or equal to 24", since that really sounds like it should mean 1-24 . . . – ruakh Commented Jan 13, 2016 at 4:52
• 2 Agree. Are arbitrarily big negative numbers supposed to pass this regex expression? Say, -1, -24, and -5060000. – mech Commented Jan 13, 2016 at 4:54
• 2 Can't use just check if the value is <= 24 and >= 1 ? – chris85 Commented Jan 13, 2016 at 5:03

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2 Answers 2

Sorted by: Reset to default 7

I won't remend you to use regex just to check if a number is between the range. To pare the numbers parison operators should be used.

if (number >= 0 && number <= 24)

However, if this is not feasible/possible, you can use regex.

---

You can also use

^(2[0-4]|[01]?[0-9])$

Regex101 Demo

Explanation:

1. ^: Start of line anchor
2. 2[0-4]: Matches 2 followed by any number between 0 to 4 - Matches 20-24
3. |: OR condition in regex
4. [01]?[0-9]: [01]?: Matches 0 or 1 optionally. [0-9]: Matches any number exactly once in the range 0 to 9 - Matches 0-19

Demo

input:valid {
  color: green;
}
input:invalid {
  color: red;
}

<input pattern="(2[0-4]|[01]?[0-9])" />

---

You can use following regex

^(2[0-4])|(^[01]?[0-9])$

Regex101 Demo

^(?:[0-9]|[1][0-9]|2[0-4])$

Try this.See demo.

https://regex101./r/iJ7bT6/3

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