Strip down asset data

Summary: This removes asset data that is not used at runtime from the bundle.

Reviewed By: javache

Differential Revision: D3628486

fbshipit-source-id: 33cd579c904e0b0e29502df39a4ff92cad43367c

docs/Images.md

@@ -109,7 +109,7 @@ iOS saves multiple sizes for the same image in your Camera Roll, it is very impo
 For example, the result of `require('./my-icon.png')` might be:
 
 ```javascript
-{"__packager_asset":true,"path":"/Users/react/HelloWorld/my-icon.png","uri":"my-icon.png","width":591,"height":573}
+{"__packager_asset":true,"uri":"my-icon.png","width":591,"height":573}
 ```
 
 ## Source as an object

packager/react-packager/src/Bundler/index.js

@@ -91,6 +91,12 @@ const validateOpts = declareOpts({
   },
 });
 
+const assetPropertyBlacklist = new Set([
+  'files',
+  'fileSystemLocation',
+  'path',
+]);
+
 class Bundler {
 
   constructor(options) {
@@ -583,7 +589,10 @@ class Bundler {
 
       bundle.addAsset(img);
 
-      const code = 'module.exports=' + JSON.stringify(img) + ';';
+      const code =
+        'module.exports=' +
+        JSON.stringify(filterObject(img, assetPropertyBlacklist))
+        + ';';
 
       return new ModuleTransport({
         name: id,
@@ -630,7 +639,7 @@ class Bundler {
         type: assetData.type,
       };
 
-      const json = JSON.stringify(asset);
+      const json =  JSON.stringify(filterObject(asset, assetPropertyBlacklist));
       const assetRegistryPath = 'react-native/Libraries/Image/AssetRegistry';
       const code =
         `module.exports = require(${JSON.stringify(assetRegistryPath)}).registerAsset(${json});`;
@@ -726,4 +735,12 @@ function debouncedTick(progressBar) {
   };
 }
 
+function filterObject(object, blacklist) {
+  const copied = Object.assign({}, object);
+  for (const key of blacklist) {
+    delete copied[key];
+  }
+  return copied;
+}
+
 module.exports = Bundler;