Allow Fastboot sandbox globals to be defined.

[Ravenstine]

I've been working on a simple static blog that uses Prember and PouchDB(ember-pouch). Unfortunately, PouchDB requires the presence of fetch() and Headers in the global scope, making it incompatible with Fastboot out of the box.

I added a globals option to Prember so that global variables can be defined for the Fastboot sandbox. That way, for my purposes, fetch and Headers will be available for PouchDB in Node, thereby allowing my application to receive blog entry JSON from my CouchDB database before rendering the HTML. I imagine this option will be useful to others.

A test is included, but it's looking for the presence of a string in the DOM passed through the globals option. I couldn't think of a better way to test this feature, which is probably due to my laziness in testing with Ember, and would be open to a suggestion on how to better test the globals option.

[ef4]

Thanks for working on this.

But I think it should be possible to solve your problem without needing a feature at this layer.

For example, to polyfill fetch in fastboot (and therefore in Prember):

1. npm install --save-dev node-fetch

2. Edit your package.json to put node-fetch in the fastboot whitelist:

    "fastbootDependencies": [
      "node-fetch"
    ]
   

3. In app.js, use the polyfill only in Fastboot:

   if (typeof FastBoot !== 'undefined') {
     window.fetch = FastBoot.require('node-fetch');
   }
   

[Ravenstine]

@ef4 I thought that was working initially, but it isn't. It looks more like PouchDB(through ember-pouch) is looking for fetch during the Broccoli build, perhaps?

Here's my error summary:

ERROR Summary:

  - broccoliBuilderErrorStack: /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor.js:81164
var f$1 = fetch;
          ^

ReferenceError: fetch is not defined
    at Object.<anonymous> (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:4838:1)
    at Object.13.1 (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:12189:1)
    at o (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1)
    at r (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1)
    at /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1
    at /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1
    at /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1
    at Script.runInContext (vm.js:102:20)
    at VMSandbox.eval (/Users/Admin/workspace/prember/node_modules/fastboot/src/vm-sandbox.js:14:16)
    at /Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:156:15
    at Array.forEach (<anonymous>)
    at EmberApp.loadAppFiles (/Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:153:21)
    at EmberApp.retrieveSandboxedApp (/Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:201:10)
    at new EmberApp (/Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:59:21)
    at FastBoot._buildEmberApp (/Users/Admin/workspace/prember/node_modules/fastboot/src/index.js:114:17)
    at new FastBoot (/Users/Admin/workspace/prember/node_modules/fastboot/src/index.js:52:10)
    at Prerender.build (/Users/Admin/workspace/prember/lib/prerender.js:88:16)
  - codeFrame: fetch is not defined
  - errorMessage: Build Canceled: Broccoli Builder ran into an error with `prember` plugin. 💥
fetch is not defined
  - errorType: Build Error
  - location:
    - column: [undefined]
    - file: [undefined]
    - line: [undefined]
    - treeDir: [undefined]
  - message: Build Canceled: Broccoli Builder ran into an error with `prember` plugin. 💥
fetch is not defined
  - name: Error
  - nodeAnnotation: prember
  - nodeName: prember
  - originalErrorMessage: fetch is not defined
  - stack: /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor.js:81164
var f$1 = fetch;
          ^

ReferenceError: fetch is not defined
    at Object.<anonymous> (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:4838:1)
    at Object.13.1 (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:12189:1)
    at o (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1)
    at r (/Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1)
    at /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1
    at /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1
    at /Users/Admin/workspace/blog-test/tmp/prember-input_base_path-xyQVjWuu.tmp/assets/vendor/pouchdb/pouchdb.js:7:1
    at Script.runInContext (vm.js:102:20)
    at VMSandbox.eval (/Users/Admin/workspace/prember/node_modules/fastboot/src/vm-sandbox.js:14:16)
    at /Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:156:15
    at Array.forEach (<anonymous>)
    at EmberApp.loadAppFiles (/Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:153:21)
    at EmberApp.retrieveSandboxedApp (/Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:201:10)
    at new EmberApp (/Users/Admin/workspace/prember/node_modules/fastboot/src/ember-app.js:59:21)
    at FastBoot._buildEmberApp (/Users/Admin/workspace/prember/node_modules/fastboot/src/index.js:114:17)
    at new FastBoot (/Users/Admin/workspace/prember/node_modules/fastboot/src/index.js:52:10)
    at Prerender.build (/Users/Admin/workspace/prember/lib/prerender.js:88:16)

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