numeric and float validation not success

Question

i have a function to validate (accept only integer and float)

function isNumeric(prodFilterValue)
{
    if((parseFloat(prodFilterValue) == parseInt(prodFilterValue)) && !isNaN(prodFilterValue))
    {
        alert('numeric');       
        alert('hahahahhahaha');
        $("#valuetxt1").css('background-color', 'white');           

    }
    else
    {
        alert('HIIIIIIIIIII');
        $("#valuetxt1").css('background-color', 'grey');
    }

    return prodFilterValue;
}

the problem now is.. when validate 0.1 it will say it is not numeric.. suppose to be it is numeric.. when i put another condition

if((parseFloat(prodFilterValue) == parseInt(prodFilterValue)) && !isNaN(prodFilterValue) || (prodFilterValue % 1 !=0))

it will validate 1A as numeric

Try this method used in Backbone http://stackoverflow.com/questions/9188998/obj-length-obj-length-in-javascript — Tamil, May 04 '12 at 09:31

KooiInc · Answer 1 · 2012-05-04T10:35:22.800

Check it using Number conversion:

 !isNaN(Number([value]));
 // e.g.
 isNumber = !isNaN(Number('.3421')); //=> true
 isNumber = !isNaN(Number('nonumber.3421')); //=> false
 isNumber = !isNaN(Number('1500032')); //=> true
 // you can also just use the conversion 
 isNumber = Number('.3421'); //=> 0.3421
 isNumber = Number('nonumer.3421'); //=> NaN
 if (!isNumber) { /*...*/ }
 // a hidden goodie: Number automatically trims the parameter
 isNumber = Number('    .3421 ');   //=> 0.3421
 isNumber = Number('    .3421 \n'); //=> 0.3421

Applied to your function:

function isNumeric(prodFilterValue,thousandsDelim) {
  prodFilterValue = Number(prodFilterValue);
  return prodFilterValue 
            ? (alert('yeah!'), prodFilterValue) 
            : (alert('no sir'), false);
}

Furthermore isNaN([value]) applies an implicit Number conversion for [value], so you can use that too.

Keep in mind that Number(''), Number(null) or Number('\t\n ') all evaluate to 0 and Number(true) evaluates to 1. So, to be complete you'll have to do extra checks. Something like:

function isNumeric(prodFilterValue) {
    prodFilterValue = prodFilterValue && 
                      /stri/i.test(typeof prodFilterValue) && 
                      prodFilterValue.replace(/^\s+|\s+$/,'').length 
                       ? Number(prodFilterValue) 
                       : undefined;
    return prodFilterValue && prodFilterValue !== 0
            ? (alert('yeah!'), prodFilterValue) 
            : (alert('no sir'), false);
}

this is good but when the value is 0.. it is false.. and when I changed to === 0 it is not functioning accordingly — ct_anas, May 08 '12 at 02:24

Adil · Answer 2 · 2012-05-04T09:51:08.363

2

You can check if it is a number then would be float or integer.

function checkNumber(numb1)
{
  numb1 += "";   // to handle boolean when true / false is passed
  if(numb1.length == 0) return false; // to handle empty string like checkNumber("")

  if(isNaN(numb1))
      alert("It is a number");
  else
      alert("It is not a number");
}

edited May 04 '12 at 09:51

answered May 04 '12 at 09:27

Adil

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Well, `isNaN("")` returns false, because of type coercion to 0, same with booleans. – Joakim Johansson May 04 '12 at 09:35
You are absolutely right, thanks for making me aware of it. I have changed the code a bit please have a look – Adil May 04 '12 at 09:48

score 0 · Answer 3 · answered May 04 '12 at 09:14

That's because parseInt and parseFloat will throw away any letters after a number, and parse 4K as 4. Add an additional condition: isFinite(prodFilterValue) and that should handle those cases.

parseInt and parseFloat will only return NaN if the first character cannot be converted to a number.

Be aware though, parseInt also handles values like hexadecimal:

parseInt("0xF"); // 15

numeric and float validation not success

3 Answers3