placeholder もどき

gistfile1.js

(function($) {
  var dataKey = "phText";
  var placeholderColor = "#aaa";

  $("[placeholder]").each(function() {
    var $elem = $(this);
    var originalText  = $elem.attr("placeholder");
    var originalColor = $elem.css("color");
    $.data(this, dataKey, originalText);

    if(this.value == "") {
      this.value = originalText;
      $elem.css({color: placeholderColor});
    }

    $elem.focus(function() {
      $elem.css({color: originalColor});
      if(this.value == originalText) {
        this.value = "";
      }
    }).blur(function() {
      if(this.value == "") {
        this.value = originalText;
        $elem.css({color: placeholderColor});
      } else {
        $elem.css({color: originalColor});
      }
    });
  })

  $("form").submit(function() {
    $("[placeholder]", this).each(function() {
      if(this.value == $.data(this, dataKey)) {
        this.value = "";
      }
    });
  });
})(jQuery)