What s the difference between app render and res render in express js

Question

Docs for app render      Render a view with a callback responding with the rendered string  This is the app-level variant of res render    and otherwise behaves the same way    Docs for res render      Render a view with a callback responding with the rendered string  When an error occurs next err  is invoked internally  When a callback is provided both the possible error and rendered string are passed  and no automated response is performed    How can I figure out when to use which one

User · Answer

use app render in scenarios where you need to render a view but not send it to a client via http  html emails springs to mind

User · Answer

Here are some differences    You can call app render on root level and res render only inside a route middleware  app render always returns the html in the callback function  whereas res render does so only when you ve specified the callback function as your third parameter  If you call res render without the third parameter callback function the rendered html is sent to the client with a status code of 200    Take a look at the following examples    app render  app render  index    title   res vs app render    function err  html        console log html          logs the following string  from default index jade   lt  DOCTYPE html gt  lt html gt  lt head gt  lt title gt res vs app render lt  title gt  lt link rel  stylesheet  href   stylesheets style css  gt  lt  head gt  lt body gt  lt h1 gt res vs app render lt  h1 gt  lt p gt Welcome to res vs app render lt  p gt  lt  body gt  lt  html gt   res render without third parameter  app get   render   function req  res        res render  index    title   res vs app render           also renders index jade but sends it to the client     with status 200 and content-type text html on GET  render  res render with third parameter  app get   render   function req  res        res render  index    title   res vs app render    function err  html            console log html           res send  done                  logs the same as app render and sends  done  to the client instead     of the content of index jade   res render uses app render internally to render template files  You can use the render functions to create html emails  Depending on your structure of your app  you might not always have acces to the app object    For example inside an external route   app js  var routes   require  routes     app get   mail   function req  res           app object is available - gt  app render     app get   sendmail   routes sendmail       routes js  exports sendmail   function req  res           can t use app render - gt  therefore res render

User · Answer

along with these two variants  there is also jade renderFile which generates html that need not be passed to the client   usage-  var jade   require  jade     exports getJson   getJson   function getJson req  res        var html   jade renderFile  views test jade    some  json         res send  message   i sent json         getJson   is available as a route in app js

[node.js] What's the difference between "app.render" and "res.render" in express.js?

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