[SOLVED] Validate - numbers and decimals only for money field

[Jason28]

Hello, Could anyone please provide a working javascript function that errors if the user enters anything other than decimals and numbers in a form field?  Thanks!

[Adam]

Found this through Google in about 3 seconds:

 

function IsNumeric(sText) {
    var ValidChars = "0123456789.";
    var IsNumber=true;
    var Char;

    for (i = 0; i < sText.length && IsNumber == true; i++) { 
        Char = sText.charAt(i); 
        if (ValidChars.indexOf(Char) == -1) {
            IsNumber = false;
        }
    }

    return IsNumber;
}

 

http://www.codetoad.com/javascript/isnumeric.asp

 

Adam

[Psycho]

Found this through Google in about 3 seconds:

 

function IsNumeric(sText) {
    var ValidChars = "0123456789.";
    var IsNumber=true;
    var Char;

    for (i = 0; i < sText.length && IsNumber == true; i++) { 
        Char = sText.charAt(i); 
        if (ValidChars.indexOf(Char) == -1) {
            IsNumber = false;
        }
    }

    return IsNumber;
}

 

http://www.codetoad.com/javascript/isnumeric.asp

 

Why would you want to loop through each character when there are much better alternatives? That function also has a bug in that it would accept input with multiple decimals.

 

Of course you could use the built-in function within JavaScript, isNaN(), which will return true if the value is not a number, else it returns false.

 

function valid_number(inputVal)
{
    return (!isNaN(inputVal));
}

 

Of course, if you're talking about a currency field you might also want to round to the nearest two decimal places. However, you can handle the problem of invalid input in a few different ways:remove non-numeric characters, remove all input if any character is not valid, etc. It's up to you.

[Jason28]

Thanks mjdamato, could you also give me the code to place in the html form that is used with this function?  I tried adding:

 

onClick="javascript:valid_number('item_price');"

 

to the form field but not sure if that is the one to use.

[Psycho]

function valid_number(fieldObj)
{
    if (fieldObj.value!='' && isNaN(fieldObj.value))
    {
        alert('You must enter a valid number');
        fieldObj.select();
        fieldObj.focus();
        return false;
    }
    return true;
}

 

<input type="text" name="cost" id="cost" onchange="valid_number(this);">

[Jason28]

Thanks a lot it works