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JavaScript Number Validation (Integer)

To validate an integer in JavaScript, use a regular expression:

var NumberToTest = 15;
var IsFound = /^-?\d+$/.test(NumberToTest);
document.write(IsFound);

The ^ symbol specifies that the tested value must begin with a digit (i.e., there can be no non-numeric data before the numeric data begins). The $ symbol is similarly used to ensure that no non-numeric data comes after the numeric data.

The + symbol matches one or more occurrences of the previous item. In this case, it means that there can be one or more digits in the test string. Without this, 15 would not validate because the test would be looking for a string that started and ended with one digit.

Related Articles:
JavaScript Regular Expressions
JavaScript Regular Expression Special Characters: $ ^
JavaScript Regular Expression Plus Sign +


This entry was posted on April 10, 2007 at 5:01 am and is filed under JavaScript, Software, Web, internet, programming . You can follow any responses to this entry through the RSS 2.0 feed You can leave a response, or trackback from your own site.

21 Responses to “JavaScript Number Validation (Integer)”

  1. srinivas.m Says:
    May 21, 2007 at 6:45 am

    this is very nice and good

    Reply
  2. Garima Says:
    June 14, 2007 at 6:19 am

    This is amazing…

    Gr8 job!!!!

    Reply
  3. Integer validation in Javascript - How to check if a number is an Integer - Noticias externas Says:
    August 10, 2007 at 11:20 am

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    Reply
  4. p.LaghupathiReddy Says:
    August 24, 2007 at 10:09 am

    it is very good.

    Reply
  5. Ananyo Banerjee Says:
    September 3, 2007 at 12:55 pm

    This is fantastic……….

    Keep up the good work :)

    Reply
  6. Tridib Says:
    December 10, 2007 at 10:59 pm

    good one..gullii..

    Reply
  7. santosh Says:
    December 27, 2007 at 1:21 am

    Hey Dude,

    Its gr8 solution, keep it up

    Reply
  8. aditi Says:
    February 26, 2008 at 4:01 am

    just beyond the imagination …i liked it……gr8 job

    Reply
  9. Pillai Says:
    March 11, 2008 at 12:19 pm

    Good

    Reply
  10. Tilly Bean Says:
    June 24, 2008 at 6:20 am

    Finally an integer test that works, thank you!

    Working example:
    if (!/^-?\d+$/.test(fld.value))
    {
    fld.style.background = ‘Red’;
    error = “Please use numbers only.\n”
    }

    Reply
  12. harilal Says:
    October 6, 2008 at 2:11 am

    gr8 job

    Reply
  13. harilal Says:
    October 6, 2008 at 2:13 am

    so faar i used parseInt() and isNaN()..i think wat u r doing is mmore good..thak u very much dude

    Reply
  14. Kumar Chetan Sharma Says:
    November 14, 2008 at 5:29 am

    How about this one???

    function isNumeric(str){
    var numRegex = !/^-?\d+$/;
    return numRegex.test(str.value);
    }

    Reply
  15. Sakthivel Says:
    December 9, 2008 at 11:41 pm

    This number validation is very useful to me to implement large projects

    Reply
  16. saikrishna Says:
    January 27, 2009 at 10:12 pm

    It is a very good validation. Very simple.
    Thank you!

    Reply
  18. ahmad Says:
    February 24, 2009 at 3:34 pm

    you’re GREAT!!!!!!! awesome!
    Thank you very much :D

    Reply
  20. Rams Says:
    November 21, 2009 at 7:54 am

    Hi,

    Really nice work…

    Thanks very much

    Rams

    Reply
  21. mark n tejas Says:
    January 26, 2010 at 2:46 pm

    wow … i have tried multiple solutions and candidly didn’t think this would work… very elegant very nice … and thanks vrry much

    Reply

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