In Lieu of doing this properly

1.1_directory_structure.txt

   ./frontend
    │
    ├── /coffee
    │   ├── /models
    │   |   └── MyBaseModel.coffee
    │   |   └── MyModel.coffee
    │   ├── /routers
    │   |   └── MyRouter.coffee
    │   ├── /templates
    |   │   ├── /tmpl-dir1
    |   │   |   ├── template1.jst.eco
    |   │   |   └── template2.jst.eco
    │   |   └── tmpl-dir2
    │   ├── /views
    │   |   └── /model_views
    |   |       ├── main_view.coffee
    |   |       └── sub_view.coffee
    │   └── /lib
    │       └── /jquery.js
    |
    ├── /tasks
    |   ├── coffee.js
    |   ├── copy.js
    |   ├── ecojst.js
    |   └── fingerprint.js
    ├── /tmp
    └── frontend.json
    └── grunt.js

1_background.md

Using grunt instead of the asset pipeline.

• At the moment I have only done coffeescript compilation, not scss/css yet
• In my rails app, I have created a ./frontend directory structure like the above.
• The ./frontend/coffee dir is where your "app" goes, it can be structured however you like, and contain .js files.
• The ./tasks file contains some custom tasks I have written, I'll include them below, but they are:
  • coffee.js compile coffee-script files from ./coffee into ./tmp maintaining directory structure.
  • copy.js copy files from ./coffee into ./tmp maintaining directory structure (copies .js files across as-is.
  • ecojst.js precompile .eco templates into .js files under a JST[] namespace - trivial to switch for handlebars or any JS template language with a precompile method.
  • fingerprint.js rename a file, appending the md5sum of its contents to the filename.
• frontend.json, is sort of a manifest defining how to build/require our compiled js file. It works a lot like the sprockets manifests: list files you want to concat in coffee: []. You can use /**/, or / to glob files, and it won't pull in files twice.

2_grunt.js

//This should be elsewhere, but loads in our manifest, and converts the file list to a list of files.
var frontendConfig = require('./frontend.json')
var concatFiles = frontendConfig.coffee.map(function(f) { return "tmp/"+f+".js"});

module.exports = function(grunt) { 
  grunt.loadTasks('./tasks'); //load my local tasks
  grunt.loadNpmTasks('grunt-clean'); //load an npm task

  grunt.initConfig({
    //Empty the 'tmp' directory on each run'
    clean: {
      folder: 'tmp'
    },
    //Compile coffeescript into tmp, maintaining directory structure, but stripping /coffee from the start
    coffee: {
      all: {
        srcRelTo: 'coffee',
        src: ['coffee/**/*.coffee'],
        dest: 'tmp',
      }
    },
    //Precompile eco templates into tmp, maintaining directory structure, but stripping /coffee from the start
    ecojst: {
      all: {
        srcRelTo: 'coffee',
        src: ['coffee/**/*.jst.eco'],
        dest: 'tmp'
      }
    },
    //Copy javascript files into tmp, maintaining directory structure, but stripping /coffee from the start
    copy: {
      all: {
        srcRelTo: 'coffee',
        src: ['coffee/**/*.js'],
        dest: 'tmp'
      }
    },
    //Using our manifest file config, concat the list of files into one
    concat: {
      frontend: {
        src: concatFiles,
        dest: frontendConfig.dest,
        separator: ';'
      }
    },
    //Using our manifest file config, minify, the manifest file
    min: {
      release: {
        src: [frontendConfig.dest],
        dest: frontendConfig.destMin
      }
    },
    //Fingerprint the minified file
    fingerprint: {
      release: {
        files: [frontendConfig.destMin]
      }
    },
    //Recompile debuggable file on change
    watch: {
      coffee: {
        files: ['coffee/**/*.coffee'],
        tasks: 'debug'
      },
    }
  });

  // Create a debuggable file
  grunt.registerTask('debug', 'clean coffee copy ecojst concat');
  // Create a releaseable file
  grunt.registerTask('release', 'debug min fingerprint');

  // Make the default `grunt` command run debug.
  grunt.registerTask('default', 'debug');
};

3_frontend.json

{
  "name": "Frontend",
  "dest": "../public/javascripts/frontend.js",
  "destMin": "../public/javascripts/frontend.min.js",

  "coffee": [
    "lib/jquery",
    "lib/**/*", 

    "templates/**/*",    

    "models/MyBaseModel",
    "models/**/*",

    "views/**/*",

    "routers/**/*",
  ]

}

4_task_coffee.js

module.exports = function(grunt) {
  var path = require('path');

  // Please see the grunt documentation for more information regarding task and
  // helper creation: https://github.com/cowboy/grunt/blob/master/docs/toc.md

  // ==========================================================================
  // TASKS
  // ==========================================================================

  grunt.registerMultiTask('coffee', 'Compile CoffeeScript files', function() {
    var dest = this.file.dest;
    var srcRelTo = this.data.srcRelTo;
    grunt.file.expandFiles(this.file.src).forEach(function(filepath) {
      
      var coffeeDir = path.dirname(filepath);
      var coffeeDir = coffeeDir.replace(srcRelTo, '');

      grunt.helper('coffee', filepath, path.join(dest, coffeeDir));
    });

    if (grunt.task.current.errorCount) {
      return false;
    }
  });

  // ==========================================================================
  // HELPERS
  // ==========================================================================

  grunt.registerHelper('coffee', function(src, destPath) {
    var coffee = require('coffee-script'),
        js = '';

    var dest = path.join(destPath, 
                         path.basename(src, '.coffee') + '.js');

    try {
      js = coffee.compile(grunt.file.read(src), { bare: true });
      grunt.file.write(dest, js);
    } catch (e) {
      grunt.log.error("Unable to compile your coffee", e);
    }
  });

};

5_tasks_copy.js

module.exports = function(grunt) {
  var path = require('path');
  grunt.registerMultiTask('copy', 'Copy files', function() {
    var dest = this.file.dest;
    var srcRelTo = this.data.srcRelTo;

    grunt.file.expandFiles(this.file.src).forEach(function(filepath) {
      var outDir = path.dirname(filepath);
      var outDir = outDir.replace(srcRelTo, '');
      var outFile = path.basename(filepath)
      
      grunt.file.copy(filepath, path.join(dest, outDir, outFile));
    });

    if (grunt.task.current.errorCount) {
      return false;
    }
  });

};

6_tasks_ecojst.js

module.exports = function(grunt) {
  var path = require("path");

  grunt.registerMultiTask("ecojst",
    "Compile eco templates to JST file", function() {

    // Expand files to full paths
    var dest = this.file.dest;
    var srcRelTo = this.data.srcRelTo;

    grunt.file.expandFiles(this.file.src).forEach(function(filepath) {
      var outDir = path.dirname(filepath);
      outDir = outDir.replace(srcRelTo, "");

      grunt.helper("ecojst", filepath, dest, outDir);
    });

    if (grunt.task.current.errorCount) {
      return false;
    }
  });

  grunt.registerHelper("ecojst", function(src, destPath, outDir) {
    var eco = require("eco"),
        js = "";

    var dest = path.join(destPath, outDir,
                         path.basename(src, ".jst.eco") + ".js");
    //try {
      js += "(function() {\n";
      js += "  this.JST || (this.JST = {});\n";
      js += '  this.JST["'+outDir.slice(1)+'/'+path.basename(src, ".jst.eco")+'"] = '
      js += eco.precompile(grunt.file.read(src));
      js += "\n}).call(this);";

      grunt.file.write(dest, js);
    //} catch (e) {
    //  grunt.log.error("Unable to compile your template", e);
    //}
  });
};

7_tasks_fingerprint.js

module.exports = function(grunt) {
  var path = require('path'),
      crypto = require('crypto'),
      fs = require('fs');

  grunt.registerMultiTask('fingerprint', 'Fingerprint Files', function() {
    
    grunt.file.expandFiles(this.data.files).forEach(function(filepath) {
      var hash = crypto.createHash('md5').update(grunt.file.read(filepath)).digest("hex");

      var outpath = path.dirname(filepath);
      var filename = path.basename(filepath);

      filename = filename.replace('.', '-'+hash+'.')

      fs.renameSync(filepath, path.join(outpath, filename));
    });
  });

};