使用！ 用于正则表达式编号验证

Question

I am trying to display an error message when the user enters anything other than a number using jQuery and regex. How do I do this?

if( $(this).val().match(/^[0-9]$/) ){
    alert("Wrong input. Only numbers allowed");
}

I tried using ! but it did not work and I got no error message

if( $(this).val().match(/![0-9]/) ){
    alert("Wrong input. Only numbers allowed");
}

Answer 1

Do it like this :

if( /\D/.test($(this).val()) ){
    alert("Wrong input. Only numbers allowed");
}

\\D is any character that isn't a digit ( \\d is a digit).

Don't use match when you want to test if a string matches a pattern: it builds an useless array. What you need is test .

Now, let's imagine you want to test if the user entered a number, not just a sequence of digits. A number can be written with a sign, an exponent, a dot, etc. The proper way to test for that isn't to use a regex:

var s = $(this).val();
if (s != +s) {
    alert("Wrong input. Only numbers allowed");
}

+s is the conversion of s to a number, NaN if it isn't possible.

Answer 2

Negate the range, not the regex itself:

if( $(this).val().match(/[^0-9]/) ){
    alert("Wrong input. Only numbers allowed");
}

That will match any string containing non-numbers.

Answer 3

To deal with both integer and floating point numbers..

if( !/^\d+(?:\.\d+)?$/.test($(this).val()) ){
    alert("Wrong input. Only numbers allowed");
}