CODEWITHSUNDEEP
javascripthtmlbooleanlogicboolean-logic
underflow
underflow

Reputation: 483

Regular expressions in javascript

Hi I'm new to javascript and I have the following function:

function checkform() {
    var theForm = document.getElementById('login_form');
    var regName = /^[a-zA-Z ]+$/;
    var firstname = theForm.firstname.value;

    if (
        (firstname == "" || theForm.firstname.value.length > 30 ) &&
        (regName.test(firstName) == false)
    ) {
        alert("That is not a valid first name!");
        theForm.firstname.focus();
        return false;
    }
}

It works in the sense that it checks that the data is not empty and not greater than 30. My problem is that is currently allows the user to enter data that does not match my regex i.e. numerical data. I can not see any problems with the logic.

Thanks

Upvotes: 0

Views: 364

Answers (3)

mirrormx
mirrormx

Reputation: 4047

In your conditional statement try doing this:

if ((firstname == "" || theForm.firstname.value.length > 30 ) || (regName.test(firstname) == false)) {
    // ...
}

I've changed the "&&" (and) operator to "||" (or), because you don't need to check against both conditions (empty or longer than 30 AND not matching regexp), but just any of them (empty or longer than 30 or not mathing regexp).

Upvotes: 3

Vitthal
Vitthal

Reputation: 546

<input id="txtChar" onkeypress="return isNumberKey(event)" 
       type="text" name="txtChar">

   function isNumberKey(evt)
   {
      var charCode = (evt.which) ? evt.which : event.keyCode;
      if (charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57) || event.value > 30)
         return false;

      return true;
   }

Upvotes: 0

Sam
Sam

Reputation: 2970

Try it

 var regName = /^[a-zA-Z ]{3,30}$/;
 if (!regName.test(firstName)){ //make an error

Upvotes: 1

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