IE8不支持属性placeholder

 $(function () {
            // -- Constants --
            var PLACE_HOLDER_COLOR = "rgb(169,169,169)"; // "darkGrey" does not work in IE6
            var PLACE_HOLDER_DATA_NAME = "original-font-color";

            // -- Util Methods --
            var getContent = function (element) {
                return $(element).val();
            }

            var setContent = function (element, content) {
                $(element).val(content);
            }

            var getPlaceholder = function (element) {
                return $(element).attr("placeholder");
            }

            var isContentEmpty = function (element) {
                var content = getContent(element);
                return (content.length === 0) || content == getPlaceholder(element);
            }

            var setPlaceholderStyle = function (element) {
                $(element).data(PLACE_HOLDER_DATA_NAME, $(element).css("color"));
                $(element).css("color", PLACE_HOLDER_COLOR);
            }

            var clearPlaceholderStyle = function (element) {
                $(element).css("color", $(element).data(PLACE_HOLDER_DATA_NAME));
                $(element).removeData(PLACE_HOLDER_DATA_NAME);
            }

            var showPlaceholder = function (element) {
                setContent(element, getPlaceholder(element));
                setPlaceholderStyle(element);
            }

            var hidePlaceholder = function (element) {
                if ($(element).data(PLACE_HOLDER_DATA_NAME)) {
                    setContent(element, "");
                    clearPlaceholderStyle(element);
                }
            }

            // -- Event Handlers --
            var inputFocused = function () {
                if (isContentEmpty(this)) {
                    hidePlaceholder(this);
                }
            }

            var inputBlurred = function () {
                if (isContentEmpty(this)) {
                    showPlaceholder(this);
                }
            }

            var parentFormSubmitted = function () {
                if (isContentEmpty(this)) {
                    hidePlaceholder(this);
                }
            }

            // -- Bind event to components --
            $("textarea, input[type=‘text‘]").each(function (index, element) {
                if ($(element).attr("placeholder")) {
                    $(element).focus(inputFocused);
                    $(element).blur(inputBlurred);
                    $(element).bind("parentformsubmitted", parentFormSubmitted);

                    // triggers show place holder on page load
                    $(element).trigger("blur");
                    // triggers form submitted event on parent form submit
                    $(element).parents("form").submit(function () {
                        $(element).trigger("parentformsubmitted");
                    });
                }
            });
        });