Set noEmit compiler option during broccoli processing.

Author: Marius Seritan

README.md

@@ -5,18 +5,66 @@ Enable typescript preprocessing on Ember 2.x apps.
 
 ## Installation
 
-In addition to ember-cli-typescript, [typescript](https://github.com/Microsoft/TypeScript) and [@type/ember](https://www.npmjs.com/package/@types/ember) are required.  You can install all of these at once with:
+In addition to ember-cli-typescript, the following files are required:
+
+- [typescript](https://github.com/Microsoft/TypeScript) version 2.0.0 or better
+- [@type/ember](https://www.npmjs.com/package/@types/ember)
+- [tsconfig](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html)
+
+You can setup all of these at once with:
 
 ```
 ember install "ember-cli-typescript@emberwatch/ember-cli-typescript"
 ```
 
-All 3 dependencies will be added to your package.json, and you're ready to roll!
+All dependencies will be added to your package.json, and you're ready to roll!
+
+## Configuration file
+
+
+### Problem ###
+
+The configuration file is used by both Ember
+CLI/[broccoli](http://broccolijs.com/) and [VS
+Code](http://code.visualstudio.com/)/`tsc` command line compiler.
+
+Broccoli controls the inputs and the output folder of the various build steps
+that make the Ember build pipeline. Its expectation are impacted by Typescript
+configuration properties like "include", "exclude", "outFile", "outDir".
+
+We want to allow you to change unrelated properties in the tsconfig file.
+
+### Solution ###
+
+This addon takes the following approach to allow this dual use:
+
+- is starts with the following [blueprint](https://github.com/emberwatch/ember-cli-typescript/blob/master/blueprints/ember-cli-typescript/files/tsconfig.json)
+
+- the generated tsconfig file does not set "outDir" and sets "noEmit" to true.
+  This allows you to run vscode and tsc without creating `.js` files throughout
+  your codebase.
+
+- before calling broccoli the addon removes "outDir" and sets "noEmit" and "includes"
+
+
+Please let us know if this does not satisfy your use cases by opening issues on this repo.
+
+### Customization ###
+
+You can customize this file further for your use case. For example to see the
+output of the compilation in a separate folder you are welcome to set and
+outDir and set noEmit to false. Then VS Code and tsc will generate files here
+while the broccoli pipeline will use its own temp folder.
 
 
 ## Incremental adoption
 
-Rename the files you want to check from `.js` to `.ts`.
+If you porting an existing app to typescript you can install this addon and
+migrate your files incrementally by changing their extensions from `.js` to
+`.ts`.  A good approach is to start at your leaf files and then work your way
+up. As typescript starts to find errors make sure to celebrate your (small)
+wins with your team, specially if some people are not convinced yet. We would also
+love to hear your stories.
 
 ## VSCode setup
 

lib/typescript-preprocessor.js

@@ -53,6 +53,13 @@ TypeScriptPreprocessor.prototype.toTree = function(inputNode, inputPath, outputP
   }
   config.include = ["**/*"];
 
+  // tsc needs to emit files on the broccoli pipeline, but not in the default config
+  // otherwise it compiled .js files may be created inadvertently.
+  config.compilerOptions.noEmit = false;
+  if (config.compilerOptions.outDir) {
+    delete config.compilerOptions.outDir;
+  }
+
   /*
    * Create a funnel with the type files used by the typescript compiler.
    *