Easy way to precompile Emberjs Handlebar templates with nodejs?

Question

I'm enjoying emberjs a lot and would like to take the next step in a couple of my small, mobile apps and precompile my Ember/Handlebars templates as part of my build process.

I'd prefer to stay away from messing with Ruby and would like to use node.js as I'm more comfortable with using it.

I believe what I want to use is Ember.Handlebars.precompile, but unfortunately I'm unable to load the canonical ember.js file in a node environment. Example of a naive attempt from the node repl:

> var e = require('./ember');
ReferenceError: window is not defined
    at /Users/jeremyosborne/git/projects/ldls/client/lib/emberjs/src/ember.js:5:1
    at Object.<anonymous> (/Users/jeremyosborne/git/projects/ldls/client/lib/emberjs/src/ember.js:1596:2)
    --- stack trace, you get the idea ---

I think I've already figured out how to set them up in my code so that they work correctly with my views, I just want to compile them in an environment outside of a browser DOM.

In lieu of getting the canonical ember.js to load in node, are there a specific set of files that I can pluck from the ember repo and use to compile my templates?

EDIT I did a kluge fix that works great but gets an F for maintainability. I grabbed all the Handlebars code minus the reference to the window object. Then I followed with the Ember.Handlebars.Compiler code, replacing Ember.create with Object.create, exporting my Ember object, and viola things work seemingly great in node (as in it works and the functions produced are templates). But I don't consider this an answer to my own question due to the aforementioned maintainafail, so still open for answers.

EDIT 2 The above turns out to be a total fail. Perhaps there's something wrong in the procedure, but using Ember.Handlebars.precompile or Ember.Handlebars.compile doesn't work. The templates get made, but when I use the precompiled templates attached to Ember.TEMPLATES in my code, they do not work. I only seem to be able to get templates to work when they are explicitly passed in the modified script tags, as suggested on the emberjs.com site.

EDIT 3 I figured out what I was doing wrong. My answer is below.

Answer 1

I've written a grunt plugin called grunt-ember-handlebars that does exactly this. It pretty much mimics Garth's script, with one important difference:

It uses lib/headless-ember.js and lib/ember.js, which are maintained (at least for now) by ember.js to precompile default templates. If you don't want to use grunt, you can extract the relevant code from the precompile_handlebars helper in tasks/ember-handlebars.js.

Answer 2

Found a good enough solution to my problem that seems easy enough to maintain that I'll consider my problem solved.

Here's how I solved things:

• Grab the minimal amount of code I need to precompile the ember templates.
  • Copy the contents of the ember handlebars into a file. This file is located at the emberjs repo: https://github.com/emberjs/ember.js/blob/master/packages/handlebars/lib/main.js
  • Within the code, find the one instance of window.Handlebars = Handlebars; and remove it.
  • Append the contents of the Ember template compiler and handlebar overrides. The file is located at the emberjs repo: https://github.com/emberjs/ember.js/blob/master/packages/ember-handlebars/lib/ext.js
  • Find all instances of Ember.create and change to Object.create.
• Outline of the simple precompile procedure:
  • Load up the code with a var Ember = require('./my_ember_precompiler').Ember.
  • Get your templates as strings and compile them with var templateString = Ember.Handlebars.precompile(str).toString().
  • This will be different from app to app, but Ember seems to require registration of precompiled templates. After loading, for every created template, we need to register our templates. Basically wrap templateString in a call to Handlebars.template() and make sure this wrapped function is added to the Ember.TEMPLATES object.

The above is painless when it's automated in a script.

Answer 3

I've published a version of ember-precompiler with a similar interface to the handlebars command line utility. You can install it from NPM:

npm install -g ember-precompile

and then run it as:

ember-precompile template... [-f OUTPUT_FILE]

It does essentially what you describe (and what the gist versions do too): mock out the missing components needed to run Ember and Handlebars, compile the templates and add them to Ember.TEMPLATES.

Answer 4

Take a look at the npm package Ember-Runner

Answer 5

The following gist contains a nodejs build script that will precompile all .handlebars files in a given folder:

https://gist.github.com/1622236

Answer 6

I wrote an official precompiler npm module for anyone else who might be wanting to do this w/ a recent version of ember.js

https://npmjs.org/package/ember-template-compiler

It's simple to install and use (example below)

npm install ember-template-compiler

var compiler = require('ember-template-compiler');
var template = fs.readFileSync('foo.handlebars').toString();
var input = compiler.precompile(template).toString();
var output = "Ember.TEMPLATES['foo'] = Ember.Handlebars.template(" + input + ");";

Answer 7

Look at the code for the official ember-rails gem at https://github.com/emberjs/ember-rails

While it's not a node.js project, it does show you how to precompile the templates using the Rails 3.1+ asset pipeline, and it includes all the necessary Javascript code that you would need to do it in Node without having to hack together a solution that you'd have to maintain on your own.

More specifically, look at vendor/assets/javascripts/ember-precompiler.js and lib/ember-rails/hjs_template.rb

I'm far from an expert on Node (obviously, Rails is more my thing).. but I think those two files should point you in the right direction. Basically, you're going to want to concatenate ember-precompiler.js (which acts as a "shim" for lack of a better word) with ember.js and then call EmberRails.precompile to compile your templates.

Answer 8

window object can be mocked by jsdom

    var jsdom = require("jsdom").jsdom;
    global.document = jsdom("<html><head></head><body></body></html>");
    global.window = document.createWindow();
    global.$ = global.jQuery = window.$ = window.jQuery = require("jquery");
    global.Handlebars = window.Handlebars = require('handlebars');
    global.Application = window.Application = {};
    require('ember.js');

and now you can run anything from Ember including Ember.Handlebars.compile