jquery - HTML5 validation before ajax submit

Question

This should be simple, yet it's driving me crazy. I have an html5 form that I am submitting with ajax. If you enter an invalid value, there is a popup response that tells you so. How can I check that the entries are valid before I run my ajax submit?

form:

<form id="contactForm" onsubmit="return false;">
  <label for="name">Name:</label>
  <input type="text" name="name" id="name" required placeholder="Name" />
  <label for="subject">Subject:</label>
  <input type="text" name="subject" id="subject" required placeholder="Subject" />
  <label for="email">Email:</label>
  <input type="email" name="email" id="email" required placeholder="email@example.com" />
  <label for="message">Message:</label>
  <textarea name="message" id="message" required></textarea>
  <input type="submit" id="submit"/>
</form>

submit:

$('#submit').click(function(){
    var name = $("input#name").val();
    var subject = $("input#subject").val();
    var email = $("input#email").val();
    var message = $("input#message").val();

    var dataString = 'email=' + email + '&message=' + message + '&subject=' + subject + '&name=' + name ; 

    $.ajax({
        url: "scripts/mail.php",
        type:   'POST',
        data: dataString,
        success: function(msg){
            disablePopupContact();
            $("#popupMessageSent").css("visibility", "visible");
        },
        error: function() {
            alert("Bad submit");
        }
    });
});

Answer 1

If you bind to the submit event instead of click it will only fire if it passes the HTML5 validation.

It is best practice to cache your jQuery selectors in variables if you use it multiple times so you don't have to navigate the DOM each time you access an element. jQuery also provides a .serialize() function that will handle the form data parsing for you.

var $contactForm = $('#contactForm');

$contactForm.on('submit', function(ev){
    ev.preventDefault();

    $.ajax({
        url: "scripts/mail.php",
        type:   'POST',
        data: $contactForm.serialize(),
        success: function(msg){
            disablePopupContact();
            $("#popupMessageSent").css("visibility", "visible");
        },
        error: function() {
            alert("Bad submit");
        }
    });
});