What is the difference between setting a property on app.locals and calling app.set()?

Question

I\'m in the process of learning Express - and thinking of the best place to save config style data. Options available are either in app.locals or app.set (settings)... so:

Answer 1

Wow, all of the answers are wrong, so let me give it a try. Despite what others say assinging to the app.local argument is different from using app.set(). Watch,

app.js
  app.locals.foo = 'bar';
  app.set('baz', 'quz');  


index.jade
  block content                            
    dl                                     
      dt app.locals.foo = 'bar';            
      dd \#{settings.foo} = #{settings.foo}
      dd \#{foo} = #{foo}                  

      dt app.set('baz', 'quz')             
      dd \#{settings.baz} = #{settings.baz}
      dd \#{baz} = #{baz}

If you ran this code, what you would see is,

app.locals.foo = 'bar';
  #{settings.foo} =
  #{foo} = bar
app.set('baz', 'quz')
  #{settings.baz} = quz
  #{baz} =

The reason for this is setting app.locals sets attributes of the object that the view uses as its environment; what the view will read from without qualification. Conversely, app.set sets attributes on app.locals.settings. You can verify this if you clobber app.locals.settings in the above with app.locals.settings = {}, which will make #{settings.baz} undefined.

So which do you use? If it's not an app setting based on the response (res.set) or global configuration (app.set), use the direct write to app.locals.