HTML5 and JavaScript验证表单

(function () {
    var inputs = document.Element('input');
    var supports = {};
    supports.autofocus = 'autofocus' in inputs;
    supports.required = 'required' in inputs;
    supports.placeholder = 'placeholder' in inputs;
    if (!supports.autofocus) { }
    if (!supports.required) { }
    if (!supports.placeholder) { }
    var send = document.getElementById('contact-submit');
    if (send) {
        send.onclick = function () {
            this.innerHTML = '...Sending'
        }
    }
})();