feat: allow publish rc versions

.travis.yml

@@ -10,9 +10,19 @@ script:
   - if [ "${TRAVIS_PULL_REQUEST}" != "false" ]; then npm audit; else npm audit || true; fi
   - npm run lint
   - npm test
-  - if [ -n "${TRAVIS_TAG}" ]; then npm version --no-git-tag-version "${TRAVIS_TAG}"; fi
+  - if [[ "${TRAVIS_TAG}" =~ ^[0-9]+\.[0-9]+\.[0-9]+(-rc\.[0-9]+)?$ ]]; then npm version --no-git-tag-version "${TRAVIS_TAG}"; fi
 
 deploy:
+  # Publish npm package with tag "next" on release candidates
+  - provider: npm
+    email: "${NPMJS_EMAIL}"
+    api_key: "${NPMJS_API_KEY}"
+    tag: next
+    skip_cleanup: true
+    on:
+      tags: true
+      condition: ${TRAVIS_TAG} =~ ^[0-9]+\.[0-9]+\.[0-9]+(-rc\.[0-9]+)$
+  # Publish npm package as "latest" on release
   - provider: npm
     email: "${NPMJS_EMAIL}"
     api_key: "${NPMJS_API_KEY}"