（obj || {}）vs Object（obj）

Question

（1）和（2）之间是否有任何重要的差异（语义，表现相关等）？

1. var obj = obj || {};
2. var obj = Object(obj);

上下文。第一个是我在Django的模板和我的js文件中共享变量的方式。我刚刚在Rauschmayer 2014中看到了一个部分（＆＃34;转换布尔，数字，字符串和对象的函数＆＃34;，第79页），他将Object(obj)描述如下：

• obj如果obj是对象，
• {}如果obj为undefined或null，
• [wrapped primitive]如果obj是原始值。

鉴于（非常非正式）语义（特别是前两个条款），在我看来，我们可以使用（2）我们将使用的任何地方（1），但我不完全确定这会产生什么后果有

_{Rauschmayer，Axel（2014）Speaking JavaScript（免费在线阅读）。}

Answer 1

是的，因为您提到的引用已经提及，所以存在差异。当## app/config/routes.rb Rails.application.routes.draw do ## Site's Root Route root 'pages#home' ## Static Page Routes get 'home' => 'pages#home' get 'about' => 'pages#about' get 'contact' => 'pages#contact' get 'privacy' => 'pages#privacy' get 'sitemap' => 'pages#sitemap' ## Administrative Routes get 'admin/dashboard' get 'admin/moderate_users' get 'admin/moderate_events' get 'admin/moderate_event_items' get 'admin/moderate_companies' get 'admin/moderate_locations' get 'admin/moderate_stories' ## Customed Devise Routes devise_for :users, :skip => [:sessions, :registrations] devise_scope :user do get "login", to: "devise/sessions#new", as: :new_user_session post "login", to: "devise/sessions#create", as: :user_session delete "logout", to: "devise/sessions#destroy", as: :destroy_user_session get "register", to: "devise/registrations#new", as: :new_user_registration post "register", to: "devise/registrations#create", as: :user_registration get "account/delete", to: "devise/registrations#cancel", as: :cancel_user_registration get "user/profile/edit", to: "devise/registrations#edit", as: :edit_user_registration patch "user", to: "devise/registrations#update" put "user", to: "devise/registrations#update" put "register", to: "devise/registrations#update" delete "user/delete", to: "devise/registrations#destrony" get "user/profile", to: 'devise/registrations#edit', as: :user_root end end 是原语时，第一个表示法将返回原语。第二个将返回一个包装的原语，它是一个对象。

如果其余代码依赖于obj作为对象，则第二种符号更具防御性。

但话又说回来，第一种符号更常见，人们可能想知道如何将原始值分配给名为obj的变量。