jQuery plugin providing feature detection and cross-browser fallback for html5 input placeholder

jquery-placeholders.js

/* Placeholders plugin for jQuery
*  Use this to provide a graceful fallback for browsers not supporting the html5 placeholder attribute
*
*  Usage:
*  jQuery('form').placeholders(); // if the user's browser do not support placeholder, it implements a fallback
*
*  You can also specify some options:
*  jQuery('form').placeholders({
*    placeholderAttr: "title",           // specify the attribute to get placeholder value from (default: 'placeholder')
*    placeholderedClass: "custom-class"  // the class added to the input element when its value is a placeholder (default 'placeholdered')
*  });
*  
*  Luca Ongaro
*/
(function($) {
  $.fn.placeholders = function(opts) {
    var defaultOpts = {
          placeholderedClass: "placeholdered",
          placeholderAttr: "placeholder"
        },
        hasPlaceholderSupport = function() {
          var input = document.createElement('input');
          return ('placeholder' in input);
        },
        setPlaceholder = function(elem) {
          elem.val(elem.attr(opts.placeholderAttr));
          elem.addClass(opts.placeholderedClass);
        },
        clearPlaceholder = function(elem) {
          if (elem.val() == elem.attr(opts.placeholderAttr)) {
            elem.val("");
          }
          elem.removeClass(opts.placeholderedClass);
        };
    opts = $.extend(defaultOpts, opts);
    // Check placeholder support
    if (!hasPlaceholderSupport() || opts.placeholderAttr != "placeholder") {
      this.find("input["+opts.placeholderAttr+"]").each(function() {
        var $input = $(this);
        // Set value to placeholder when empty
        if ($input.val() == '') {
          setPlaceholder($input);
        }
        // Clear placeholder when focus
        $input.on("focus change", function() {
          if($input.hasClass(opts.placeholderedClass)) {
            clearPlaceholder($input);
          }
        }).blur(function() {
          if(!$input.hasClass(opts.placeholderedClass) && $input.val() == "") {
            setPlaceholder($input);
          }
        });
        // Clear placeholder on submit
        $input.closest("form").submit(function() {
          if($input.hasClass(opts.placeholderedClass)) {
            clearPlaceholder($input);
          }
        });
      });
    }
  };
})(jQuery);