From b10662050e5f3e3da01124ade6a21175f8a65b5e Mon Sep 17 00:00:00 2001
From: Mehmet Bektas <mbektas@bloomberg.net>
Date: Wed, 8 Jan 2020 17:11:56 +0100
Subject: [PATCH] prevent npm install, yarn install should be used

---
 .npmrc       | 1 +
 package.json | 5 +++++
 2 files changed, 6 insertions(+)
 create mode 100644 .npmrc

diff --git a/.npmrc b/.npmrc
new file mode 100644
index 0000000000..c42da845b4
--- /dev/null
+++ b/.npmrc
@@ -0,0 +1 @@
+engine-strict = true
diff --git a/package.json b/package.json
index e4977920ff..9faa3f3bf3 100644
--- a/package.json
+++ b/package.json
@@ -5,6 +5,11 @@
     "widgetsnbextension",
     "examples/*"
   ],
+  "engines": {
+    "npm": "please-use-yarn",
+    "node": ">=10.15.3",
+    "yarn": ">=1.15.0"
+  },
   "scripts": {
     "build": "lerna run build --ignore \"@jupyter-widgets/example-*\"",
     "build:examples": "lerna run build --scope \"@jupyter-widgets/example-*\" --include-filtered-dependencies",