JQUERY 插件:placeholder(转自个人百度空间)

[mishe]

$.fn.extend({
        placeholder:function () {
            if ("placeholder" in document.createElement("input")) {
                return this //如果原生支持placeholder属性，则返回对象本身
            } else {
                return this.each(function () {
                    var _this = $(this);
                    if(_this.attr('type')!='password'){
                        _this.val(_this.attr("placeholder")).focus(function () {
                            if (_this.val() === _this.attr("placeholder")) {
                                _this.val("")
                            }
                        }).blur(function () {
                                if (_this.val().length === 0) {
                                    _this.val(_this.attr("placeholder"))
                                }
                            });
                    }else{
                        var newObj=$('<input type="text" value="'+_this.attr('placeholder')+'" autocomplete="off" class="'+_this[0].className+'" />');
                        _this.hide().after(newObj);
                        newObj.focus(function(){
                            newObj.hide();
                            _this.show().focus();
                        });
                        _this.blur(function(){
                            if(_this.val() == '') {
                                newObj.show();
                                _this.hide();
                            }
                        });
                    }
                })
            }
        }
    });