Javascript: Validate a field: Not empty & only contains numbers

Question

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Validate numbers in JavaScript - IsNumeric()

Hi I am trying to validate a field using javascript to ensure that the field is not empty AND only contains numbers

I am using document.getElementById to get the value of the field, then using this function to validate it:

function isNumeric(elem, message, messsage2)
{
   if(isNaN(elem))
   { 
    alert(message2); 
    return false; 
   }
   else if (elem == null || elem =="")
   {
    alert(message);
    return false;
   }
return true;
}

However this function still allows me to enter letters as where there should be numbers

do you think you are the first person trying to validate number with javascript in 2012? :) see [this](http://stackoverflow.com/q/1779013/944681) or [this](http://stackoverflow.com/q/18082/944681) — Michal Klouda, Oct 06 '12 at 18:45
both those posts are validating numbers, i need a function that validates not empty and only numbers. — Neil, Oct 06 '12 at 18:57

score 1 · Answer 1 · answered Oct 06 '12 at 18:43

1

function isNonEmptyNumber (str) {
  if(!str.length) return false;
  var num = +str;
  return isFinite(num) && !isNaN(num);
}

answered Oct 06 '12 at 18:43

Peter Olson

139,199
49
202
242

score 0 · Answer 2 · answered Oct 06 '12 at 18:47

0

With regexp:

value.match(/^\d+$/)

answered Oct 06 '12 at 18:47

Chocimier

48
2
5

This will fail to match numbers like `1.2`, `-1`, etc. – NullUserException Oct 06 '12 at 18:48
Yes, but then you'd get false positives like `+++++` or `.` – NullUserException Oct 06 '12 at 18:58

Javascript: Validate a field: Not empty & only contains numbers

2 Answers2