Conditionally allow assets to be loaded without a manifest. Update README to document available options.

README.md

@@ -41,6 +41,16 @@ the asset manifest. This defaults to `[ 'js', 'css' ]`.
 _Note: This class provides default `contentFor`, `postprocessTree`, and `postBuild` hooks so be sure that you call
 `_super` if you override one of those methods._
 
+### Options
+
+##### noManifest
+* Type: `boolean`
+* If `true`, a <meta> tag which would eventually hold the manifest will not be inserted into the DOM.
+
+##### noManifestLookup
+* Type: `boolean`
+* If `true`, no error will be thrown in the event that a manifest was not generated for the current environment
+
 ### Why isn't a manifest generated by default?
 
 This addon doesn't perform manifest generation just by virtue of being installed because there is no convention for

app/config/asset-manifest.js

@@ -1,24 +1,30 @@
 import require from 'require';
 import environment from './environment';
 
+
 const modulePrefix = environment.modulePrefix;
 const metaName = `${modulePrefix}/config/asset-manifest`;
 const nodeName = `${modulePrefix}/config/node-asset-manifest`;
 
 let config = {};
+const lookupManifest = !environment.noManifestLookup;
 
-try {
-  // If we have a Node version of the asset manifest, use that for FastBoot and
-  // similar environments.
-  if (require.has(nodeName)) {
-    config = require(nodeName).default; // eslint-disable-line
-  } else {
-    const rawConfig = document.querySelector('meta[name="' + metaName + '"]').getAttribute('content');
-    config = JSON.parse(unescape(rawConfig));
+if (lookupManifest) {
+  try {
+    // If we have a Node version of the asset manifest, use that for FastBoot and
+    // similar environments.
+    if (require.has(nodeName)) {
+      config = require(nodeName).default; // eslint-disable-line
+    } else {
+      const rawConfig = document.querySelector('meta[name="' + metaName + '"]').getAttribute('content');
+      config = JSON.parse(unescape(rawConfig));
+    }
+  } catch(err) {
+    throw new Error('No manifest was found with the name "' + metaName +
+      '". To hide this message you can set the config option `noManifestLookup` to `true`. For non-browser environments, verify that you included the node-asset-manifest module.', {
+        id: 'no-manifest-found'
+      });
   }
-} catch(err) {
-  throw new Error('Failed to load asset manifest. For browser environments, verify the meta tag with name "'+ metaName +
-    '" is present. For non-browser environments, verify that you included the node-asset-manifest module.');
 }
 
 export default config;