Javascript input Validation

[THT]

I need to validate a Text box using javascript

Id like to do it on keypress so that if a user enters a character they shouldnt, it displays a message.

The only characters that should be allowed are A-Z 0-9 and all punctuation
Im trying to do this to avoid people entering foreign characters such as Ĉ è æ

Should I do this using a regular expression?
Whats the easiest way to do this?

 

[riddlermarc]

Some sort of onchange to call a function that verifies the contents of the box, shouldn't be too hard

Check out http://www.w3schools.com/jsref/jsref_onchange.asp and change the "upperCase" function to check for valid characters rather than capitalising

 

[THT]

yeah you can use the onkeypress event

Its just I dont want to have to specify every character im allowing

A-Z 0-9 ,.><??'@;{[}]#~

Theres a lot of punctuation characters which I want to allow.... just not the foreign characters

 

[roboffer]

You could use the onchange or one of the onkey events and a regular expression - however that all depends on your knowledge of regular expressions and if the expression is complex then you may struggle. Alternatively you can either list the accepted or rejected characters in a string and just perform an indexOf() using the last character in your string but as you say the list could become long.

Using a regular expression is probably your best bet, but Im struggling to understand what you are after? You seem to havea grasp of the concept of what yo uare doing, do you need help with anything in particular?

 

[THT]

Thanks Rob,

I need to know if theres a way (or maybe the actual regexp?) for english chars only with punctuation.

Excluding things like Ĉ è æ ....

 

[roboffer]

Dont have time to look myself but a good starting point is

http://regexlib.com/default.aspx