simple regex in javascript returning true when it shouldn't be

Asked Jul 27 '18 at 12:34

Active Jul 27 '18 at 15:22

Viewed 28 times

I have the following regular expression to only accept alphanumeric characters and a space char.

/[a-zA-Z0-9 ]*$/

Works fine on my server side validation (c#), however on my client side it's returning true for values like $£"%$£"%^£.

What gives?

Here's the client side code:

$.validator.addMethod('alphanumeric', function (value, element, regexp) {
    if (regexp.constructor != RegExp)
        regexp = new RegExp(regexp);
    else if (regexp.global)
        regexp.lastIndex = 0;
    return regexp.test(value);
}, 'Please only enter alphanumeric characters (a-z, 0-9)');

$('#PredictedA2, #GCSE').rules("add", { alphanumeric: /[a-zA-Z0-9 ]*$/ });

edited Jul 27 '18 at 15:22

Sparky

98,165
25
199
285

asked Jul 27 '18 at 12:34

Sean T

2,414
2
17
23

1

Are you sure it is not `/^[a-zA-Z0-9 ]*$/`? – Wiktor Stribiżew Jul 27 '18 at 12:35
@WiktorStribiżew That regex works on server side `[a-zA-Z0-9 ]*$` – Sean T Jul 27 '18 at 12:36
2

But you need `^` to match the start of the string, change to `^[a-zA-Z0-9 ]*$` – Wiktor Stribiżew Jul 27 '18 at 12:36
@WiktorStribiżew Bingo... add as answer and I'll accept buddy – Sean T Jul 27 '18 at 12:38
Your answer is [here](https://stackoverflow.com/a/6298587/3832970). – Wiktor Stribiżew Jul 27 '18 at 12:39
1

It feels like the confusion might be more "why is this matching" vs "how to match a whole string". If this is the case, the duplicate answer works because your existing regex basically matches anything _ending_. More specifically, it matches zero or more characters from within the set followed by the end of the string, so, in other words, any string that ends. – Fissure King Jul 27 '18 at 12:40

simple regex in javascript returning true when it shouldn't be

0 Answers0