Question

I have used the below regex expression to check alphabets, numbers, characters, + and –

if (/[^a-z0-9\-\+]+$/i.test(value)) 
        {
            alert ("Only alphabets and numbers are allowed.");
            return;
        }

This shows the message if any special characters is used. But one problem i am facing is if the value is a combination of special characters and alphabets or numbers then this condition does not satisfy. For example if the value is %$2 then the condition does not return true and show the message. I want that if any special character is present then the condition should satisfy and show the message.

Answer 1

You should not use the $ anchor. Also the final + is not necessary in your case. The following checks whether the string contains any disallowed characters:

if (/[^a-z0-9\-\+]/i.test(value)) 
{
    alert ("Only alphabets and numbers are allowed.");
    return;
}

You could also invert the condition. (Use * or + depending on whether you allow empty string.) The following checks whether the whole string only contains the allowed characters:

if (!/^[a-z0-9\-\+]*$/i.test(value)) 
{
    alert ("Only alphabets and numbers are allowed.");
    return;
}