jQuery plugin for html5 placeholder backward compatibility

placeholder.js

/**
 * Placeholder - jQuery Plugin
 * Emulates the html5 placeholder effect on older browsers
 *
 * Copyright (c) 2014 Roger 'SparK' Rodrigues da Cruz
 *
 * Version: 0.3 (14/02/2014)
 * Requires: jQuery
 *
 * Dual licensed under GPL and MIT:
 *   http://www.gnu.org/licenses/gpl.html
 *   http://www.opensource.org/licenses/mit-license.php
 */
;(function($){
	$.fn.placeholder = function(options){
		if("placeholder" in document.createElement("input")) return;

		var opt = {
			type: "auto",
			disabledColor: "#7f7f7f"
		}
		$.extend(opt,options);

		$(this).each(function(){
			var obj = {
				element: this,
				color: $(this).css("color"),
				type: (opt.type=="auto")?$(this).attr("type"):opt.type,
				text: $(this).val() == ''?$(this).attr("placeholder"):$(this).val(),
				active: true,
				tryEnable: function(){
					if(this.active) return;

					$(this.element).val("");
					$(this.element).css("color",this.color);
					if(this.type == "password" && $.browser.firefox)
						$(this.element).attr("type","password");
					this.active = true;
				},
				tryDisable: function(){
					if(!this.active) return;
					if(!!$(this.element).val()) return;

					$(this.element).val(this.text);
					$(this.element).css("color",opt.disabledColor);
					if(this.type == "password" && $.browser.firefox)
						$(this.element).attr("type","text");
					this.active = false;
				}
			}

			obj.tryDisable();

			$(obj.element).keyDown(function(){
				obj.tryEnable();
			});
			$(obj.element).blur(function(){
				obj.tryDisable();
			});
			$(obj.element).parents("form").bind("reset",function(event){
				setTimeout(function(){
					$(obj.element).val("");
					obj.active = true;
					obj.tryDisable();
				},0);
			});
			$(obj.element).parents("form").submit(function(event){
				obj.enable();
				setTimeout(function(){
					obj.tryDisable();
				},0);
			});
		});
	}
})(jQuery);