Chapter 5 Exercise Set 1

1. Being able to read the values of the form fields makes it possible to write a function validInfo, which takes a form object as its argument and returns a boolean value: true when the name field is not empty and the email field contains something that looks like an e-mail address, false otherwise. Write this function.

   function validInfo(form) {
       return form.elements.name.value != "" &&
           /^.+@.+\.\w{2,3}$/.test(form.elements.email.value);
   }
   
   alert(validInfo(document.forms.userinfo));
   

   You did think to use a regular expression for the e-mail check, didn’t you?

2. Finish the form validator by giving the button’s onclick property a new value ― a function that checks the form, submits when it is valid, or pops up a warning message when it is not. It will be useful to know that form objects have a submit method that takes no parameters and submits the form.

   userForm.elements.send.onclick = function() {
       if (validInfo(userForm))
           userForm.submit();
       else
           alert("Give us a name and a valid e-mail address!");
   };