checking if number entered is a digit in jquery

Question

I have a simple textbox in which users enter number. Does jQuery have a isDigit function that will allow me to show an alert box if users enter something other than digits?

the field can have decimal points as well.

Answer 1

I would suggest using regexes:

var intRegex = /^\d+$/;
var floatRegex = /^((\d+(\.\d *)?)|((\d*\.)?\d+))$/;

var str = $('#myTextBox').val();
if(intRegex.test(str) || floatRegex.test(str)) {
   alert('I am a number');
   ...
}

Or with a single regex as per @Platinum Azure's suggestion:

var numberRegex = /^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?$/;
var str = $('#myTextBox').val();
if(numberRegex.test(str)) {
   alert('I am a number');
   ...
}

Answer 2

jQuery is a set of JavaScript functions, right? So you could use JavaScript's regular expression support to validate the string. You can put this in a jQuery callback if you like, too, since those just take anonymously-declared function bodies and the functions are still JavaScript.

Link: http://www.regular-expressions.info/javascript.html

Answer 3

Value validation wouldn't be a responsibility of jQuery. You can use pure JavaScript for this. Two ways that come to my mind are:

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

Answer 4

Forget regular expressions. JavaScript has a builtin function for this: isNaN():

isNaN(123)           // false
isNaN(-1.23)         // false
isNaN(5-2)           // false
isNaN(0)             // false
isNaN("100")         // false
isNaN("Hello")       // true
isNaN("2005/12/12")  // true

Just call it like so:

if (isNaN( $("#whatever").val() )) {
    // It isn't a number
} else {
    // It is a number
}

Answer 5

With jQuery's validation plugin you could do something like this, assuming that the form is called form and the value to validate is called nrInput

$("form").validate({
            errorElement: "div",
            errorClass: "error-highlight",
            onblur: true,
            onsubmit: true,
            focusInvalid: true,
            rules:{
                'nrInput': {
                    number: true,
                    required: true
                }
            });

This also handles decimal values.