(function() {
    if (window.addEventListener) window.addEventListener("load", init, false);
    else if (window.attachEvent) window.attachEvent("onload", init);
    function init() {
        for(var i = 0; i < document.forms.length; i++) {
            var f = document.forms[i];
            var needsValidation = false;
            for(j = 0; j < f.elements.length; j++) {
                var e = f.elements[j];
                if (e.type != "text") continue;
                var pattern = e.getAttribute("pattern");
                var required = e.getAttribute("required") != null;
                if (required && !pattern) {
                    pattern = "\\S";
                    e.setAttribute("pattern", pattern);
                }
                if (pattern) {
                    e.onchange = validateOnChange;
                    needsValidation = true;
                }
            }
            if (needsValidation) f.onsubmit = validateOnSubmit;
        }
    }
    function validateOnChange() {
        var textfield = this;
        var pattern = textfield.getAttribute("pattern");
        var value = this.value;
        if (value.search(pattern) == -1) textfield.className = "invalid";
        else textfield.className = "valid";
    }
    function validateOnSubmit() {
        var invalid = false;
        for(var i = 0; i < this.elements.length; i++) {
            var e = this.elements[i];
            if (e.type == "text" && e.onchange == validateOnChange) {
                e.onchange();
                if (e.className == "invalid") invalid = true;
            }
        }
        if (invalid) {
            alert("The form is incompletely or incorrectly filled out.\n" +
                  "Please correct the  highlighted fields and try again.");
            return false;
        }
    }
})();