Giving choice - npm or yarn.

Summary:
Fixing issue raised in #782.
Closes #786

Differential Revision: D5394680

Pulled By: NTillmann

fbshipit-source-id: b1f9f42425e759b68fbce5aa77f6d5a02e162756

README.md

@@ -7,12 +7,17 @@ See the official [prepack.io](http://prepack.io) website for an introduction and
 
 ## How to use Prepack
 
-Install the CLI via yarn,
+Install the CLI via npm,
 
 ```bash
-$ yarn global add prepack
+$ npm install -g prepack
 ```
-Or if you prefer yarn,
+
+Or if you prefer yarn, make sure you get yarn first,
+```bash
+$ npm install -g yarn
+```
+and then install the Prepack CLI via yarn:
 
 ```bash
 $ yarn global add prepack
@@ -49,6 +54,8 @@ Detailed instructions and the API can be found at [Prepack CLI: Getting Started]
 3. Get yarn and node, then do
    `yarn`
 
+Note: For development work you really need `yarn`, as many scripts require it.
+
 ### How to build, lint, type check
 
 0. Get the code

package.json

@@ -23,7 +23,7 @@
   "main": "lib/prepack-node.js",
   "browser": "lib/prepack-standalone.js",
   "scripts": {
-    "build": "babel src --out-dir lib --source-maps && npm run build-bundle",
+    "build": "babel src --out-dir lib --source-maps && yarn build-bundle",
     "build-scripts": "babel scripts --out-dir lib",
     "build-bundle": "webpack",
     "watch": "babel src scripts --out-dir lib --watch --source-maps",
@@ -41,12 +41,12 @@
     "test-error-handler-with-coverage": "./node_modules/.bin/istanbul cover ./lib/test-error-handler.js --dir coverage.error && ./node_modules/.bin/remap-istanbul -i coverage.error/coverage.json -o coverage-sourcemapped.error -t html",
     "test-node-cli-mode": "bash < scripts/test-node-cli-mode.sh",
     "test-std-in": "bash < scripts/test-std-in.sh",
-    "test": "npm run test-residual && npm run test-serializer && npm run test-sourcemaps && npm run test-test262 && npm run test-internal && npm run test-error-handler && npm run test-std-in",
+    "test": "yarn test-residual && yarn test-serializer && yarn test-sourcemaps && yarn test-test262 && yarn test-internal && yarn test-error-handler && yarn test-std-in",
     "repl": "node lib/repl-cli.js",
     "prepack": "node lib/prepack-cli.js",
     "prepack-prepack": "node --stack_size=10000 --max_old_space_size=8096 ./bin/prepack.js ./lib/prepack-cli.js --out ./lib/prepack-cli.prepacked.js --compatibility node-cli --mathRandomSeed rnd",
-    "validate": "npm run build && npm run build-scripts && npm run lint && npm run depcheck && npm run flow && npm test",
-    "prepublish": "npm run build",
+    "validate": "yarn build && yarn build-scripts && yarn lint && yarn depcheck && yarn flow && yarn test",
+    "prepublish": "yarn build",
     "depcheck": "babel-node scripts/detect_bad_deps.js",
     "prettier": "node ./scripts/prettier.js write-changed",
     "prettier-all": "node ./scripts/prettier.js write",