How to log a message to the console in Handlebars?

I'm not sure why Ember.Handlebars.helper doesn't work... As of now you can try

  Ember.Handlebars.registerHelper('debug', function(the_string){
    Ember.Logger.log(the_string);
    // or simply
    console.log(the_string);
  });

Just posting a new answer for people who find this in future. There is an easier way now.

Your {{debug}} helper is effectively built-in with the native {{log}} helper. You can also add a breakpoint with the {{debugger}} helper.

See the guides for more info.