How to allow all special characters in textbox only one time in JS?

[raghurox27]

Dear Programmers, please help me out in this scenario:-

I want my textbox should accept only special characters only once.

It means for example:

It should not allow '%' symbol more than once.

All the special characters should be allowed only once in my textbox in JS.

Thanx Inadvance.

[Dormilich]

you would first have to define what a "special character" is. then you would check on input if the put in character already exists in the textbox’ value.

[raghurox27]

Ohkay Thank You for your reply sir!!

But yesterday i was trying using RegEx. So Is it possible to restrict more than one same character in textbox using Regex?

[Dormilich]

you would only need the RegExp to figure out if a character is a special character. then you would use String.indexOf( ) for the test.