Question

I am doing a client side form validation to check if passwords match. But the validation function always returns undefined.

function validatePassword(errorMessage)
{
   var password = document.getElementById("password");
   var confirm_password = document.getElementById("password_confirm");

   if(password.value)
   {
      // Check if confirm_password matches
      if(password.value != confirm_password.value)
      {
         return false;
      }
   }
   else
   {
      // If password is empty but confirm password is not
      if(confirm_password.value)
      {
         return false;
      }
   }
   return true;
}

Please note that the validatePassword is called from a member function of the Form object.

function Form(validation_fn)
{
   // Do other stuff
   this.submit_btn = document.getElementById("submit");
   this.validation_fn = validation_fn;
}

Form.prototype.submit = funciton()
{
   var result;
   if(this.validation_fn)
   {
      result = this.validation_fn();
   }

   //result is always undefined
   if(result)
   {
       //do other stuff
   }
}

Answer 1

You could simplify this a lot:

• Check whether one is not empty
• Check whether they are equal

This will result in this, which will always return a boolean. Your function also should always return a boolean, but you can see it does a little better if you simplify your code:

function validatePassword()
{
   var password = document.getElementById("password");
   var confirm_password = document.getElementById("password_confirm");

   return password.value !== "" && password.value === confirm_password.value;
       //       not empty       and              equal
}