使用jQuery进行数值验证

Question

To validate that the input field contains a numeric value I'm using the isNumeric() method of jQuery:

$.isNumeric(value);

This works fine for most of the cases, but the following example fails:

$.isNumeric("0.");

This returns true while it's not a numeric value.

Is there a better way of such validation without using any other plugin?

Thanks.

Answer 1

You haven't listed all of your use cases, but I have ran through a couple in the console, including your breaking case;

You can simply cast the string to a JavaScript Number:

$.isNumeric(Number("0."))
=> true

And it seems to work with strings that aren't numbers as well.

$.isNumeric(Number("fasd"))
=> false

AMEND:

$.isNumeric(Number(0.))
=> true

$.isNumeric(Number(.0))
=> true

Also, if your DB doesn't like "0." then cast the thing:

Number(0.)
=> 0

Number(.0)
=> 0

Number(".0")
=> 0

Number("0.")
=> 0

Let me know if this solution doesn't cover your problem. Cheers!

Answer 2

Try below code.

function isNumeric(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
}

Example:

var matches = val.match(/\d+/g);
if (matches != null) {
    alert('number');
}

Answer 3

If what you want is to check the type, you can use jQuery.type() :

console.log(jQuery.type( "0." ) === "number");// False
console.log(jQuery.type( 0. ) === "number");// True

Just for completeness, using this approach of type, you could check numbers this way:

var isNumber = function(o) {
    return typeof o === 'number' && isFinite(o);
}

BTW, 0. and .0 are valid number formats in javascript.

Answer 4

The following is my solution:

!$.isNumeric(value) || value.substring(value.length - 1) == "." || value.substring(0, 1) == "."

If the result of this is false - the value is not numeric including 5. and .5 which are valid numeric values in JavaScript.

Thanks everybody for your input.