Require Node.js >= 6.0.0

sun-zheng-an · sun-zheng-an · commit 78b599e507d1 · 2019-03-03T00:50:15.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,9 +1,7 @@
 language: node_js
 node_js:
-  - "node"
-  - "6"
-  - "5"
-  - "4"
+  - 'node'
+  - '6'
 after_script:
   - npm run coveralls
 sudo: false
diff --git a/package.json b/package.json
@@ -63,6 +63,6 @@
     "through2": "^3.0.1"
   },
   "engines": {
-    "node": ">=4.8.0 <5.0.0 || >=5.7.0"
+    "node": ">=6.0.0"
   }
 }
