install step

.circleci/config.yml

@@ -10,7 +10,15 @@ jobs:
       size: "medium" # resource class, can be "medium", "large", "xlarge", "2xlarge", defaults to "medium" if not specified
 
    steps:
-      # Commands are run in a Windows virtual machine environment
       - checkout
-      - run: Write-Host 'Hello WORLD !'
+      - restore_cache:
+          key: yarn-cache{{ checksum "yarn.lock" }}
+      - run:
+          name: install-yarn
+          command : yarn global add node-gyp && yarn install
+
+      - save_cache:
+          key: yarn-cache{{ checksum "yarn.lock" }}
+          paths:
+            - ./node_modules