Javascript validation on Floating values

Question

How to do decimal validation using javascript?

There is a text box which should accept only 24.00 or 24 or any value less than 24.00. The text box also must allow if 23.99 is entered.

I tried it this way:

if (document.forms[0].hours!= undefined) {
    var val = document.forms[0].hours.value;
    if (val .match(/^\d{0,6}(?:\.\d{0,2})?$/)) {
        alert("Invalid" +'${payType}'+"  Hours. The hours entered can not have more than 2 decimal places or should be in the range of 0 to 24 ");
        submitted=false;           
        return false;
    }
}

The values can be: 1.00 or 12.25 or 1.25 or 23.99 or 24 but not above these values. Any number below 24.00 or 24.

The text box can have values like 23.99 and 24 but not above 24 — Java Questions
– Java Questions, Commented Jul 29, 2014 at 7:14

hex494D49 · Accepted Answer · 2014-07-31 08:22:36Z

2

If you prefer doing it with regex try this

^(0+)?(24(\.00?)?|(\.00?)?|\.[0-9]+|0?[0-9](\.[0-9]{0,2})?|(0+)?[0-2][0-3](\.[0-9][0-9]?)?)$

Tested on all the values below

   0.0
  4.00
  4.01
024.0
  5.8
  2.95
 10.5
 10.00
023.9
011
 09.89
 09
  8.67
 24
 24.00
 24.0
 23.99
  0.00
  0
   .5
   .55
  6
 24.01  // fail
 13.90
 78.23  // fail
  1.56
  0.06
 25.00  // fail
 23.99
 41.00  // fail

Demo

The section below isn't related to the answer but rather to the comments below. @Anto these are just a few of online resources on regex. Have fun ;)

Free online books (google for these books)

Mastering Regular Expressions, 3rdEdition
Introducing Regular Expressions
Regular Expression Pocket Reference, 2nd Edition
Regular Expressions Cookbook

Good websites

Online regex tester

http://regex101.com/

edited Jul 31, 2014 at 8:22

answered Jul 29, 2014 at 7:14

hex494D49

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13 Comments

Java Questions Over a year ago

it does not allow this value 1.56, we can enter any value below 24

Java Questions Over a year ago

it accepts this value too 24.01 but anything below 24 should be okay

ostapische Over a year ago

@hex494D49 00.00 too pass, but must be 0.00 or just 0 I think. @Anto its allows 1.56.

hex494D49 Over a year ago

@Anto As you can see there's only one fail. I'm trying to fix it :)

Java Questions Over a year ago

@hex494D49, thanks for your response. please help me to fix and let me know once you complete :) thanks

|

Avinash Raj · Accepted Answer · 2014-07-29 07:21:29Z

2

You could try the below regex,

^(?:24\.00|24|(?:[0][1-9]|[1][0-9]|2[0-3])\.[0-9][0-9])$

DEMO

OR

If you don't want 0 before the digit then you could try the below

^(?:24\.00|24|(?:[1-9]|[1][0-9]|2[0-3])\.[0-9][0-9])$

DEMO

answered Jul 29, 2014 at 7:21

Avinash Raj

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1 Comment

Java Questions Over a year ago

it should also accept 1 to 24 or 1.00 to 23.99 but your regex is not accepting any value between 1 to 24 but 1.00 to 24.00

yao lu · Accepted Answer · 2014-07-29 09:20:32Z

0

you can reverse thinking

allow any number above 24.00 or 24

var reg = /^(24\.(0[1-9]|[1-9]\d?)|([3-9]\d|[^0]\d{2,9}|2[5-9])(\.\d{1,2})?)$/

     3.33     fail
    23.00     ...
    24        ...
    24.00     ...
     0.00     ...
     0        ...
    24.01     pass
    34.01     ...
    34        ...
   120.18     ...

if (document.forms[0].hours!= undefined) {
    var val = document.forms[0].hours.value;
    if (!reg.test(val)) {
        alert("Invalid" +'${payType}'+"  Hours. The hours entered can not have more than 2 decimal places or should be in the range of 0 to 24 ");
        submitted=false;           
        return false;
    }
}

edited Jul 29, 2014 at 9:20

answered Jul 29, 2014 at 8:02

yao lu

814 bronze badges

Comments

Mowday · Accepted Answer · 2014-07-31 10:54:31Z

0

You don't need regular expression for this at all. In fact it would be a lot simpler to just do this:

if (document.forms[0].hours!= undefined) {
    var val = parseFloat(document.forms[0].hours.value);

    // Get the number of decimals
    var a = val.toString().split(".");
    var decimals = a.length > 1 ? a[1].length : 0;

    if (isNaN(val) || val < 0 || val > 24 || decimals > 2) {
        alert("Invalid" +'${payType}'+"  Hours. The hours entered can not have more than 2 decimal places or should be in the range of 0 to 24 ");
        submitted=false;           
        return false;
    }
}

edited Jul 31, 2014 at 10:54

answered Jul 31, 2014 at 7:43

Mowday

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3 Comments

Mowday Over a year ago

Fair enough, added isNaN to the if statement to protect from strings as well.

Mowday Over a year ago

Haha ok, sure. Added parseFloat to protect against empty strings. My point is: regexp for this is to overcomplicate things and will only result in messy code, especially if it's a complicated expression. A logical approach in code is something all (most) developers can read and understand. If you have more requirements, you can simply add it to the if statement.

Java Questions Over a year ago

It is true, but i did not even think the way you thought of. thanks for that. and if i enter space and execute i get Unable to get value of the property 'length': object is null or undefined

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