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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?
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The res. render() function is used to render a view and sends the rendered HTML string to the client. Syntax: res.render(view [, locals] [, callback])
app. get is called when the HTTP method is set to GET , whereas app. use is called regardless of the HTTP method, and therefore defines a layer which is on top of all the other RESTful types which the express packages gives you access to.
set() Function. The app. set() function is used to assigns the setting name to value.
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) <!DOCTYPE html><html><head><title>res vs app render</title><link rel="stylesheet" href="/stylesheets/style.css"></head><body><h1>res vs app render</h1><p>Welcome to res vs app render</p></body></html> 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 -> app.render }) app.get('/sendmail', routes.sendmail); routes.js
exports.sendmail = function(req, res) { // can't use app.render -> therefore res.render } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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