添加babel-polyfill

package.json

@@ -13,6 +13,7 @@
     "@babel/core": "^7.4.4",
     "@babel/preset-env": "^7.4.4",
     "babel-loader": "^8.0.5",
+    "babel-polyfill": "^6.26.0",
     "clean-webpack-plugin": "^2.0.1",
     "css-loader": "^2.1.1",
     "echarts": "^4.6.0",

src/js/index.js

@@ -1,4 +1,5 @@
 const $ = require("jquery");
+require("babel-polyfill");
 const echarts = require("echarts");
 require("./../css/knowledgeMap.less");
 require("./../css/common.css");

src/js/knowledgeTree.js

@@ -1,3 +1,4 @@
+require("babel-polyfill");
 require("./../css/knowledgeTree.less");
 require("./../css/common.css");
 require('./../resources/images/logo.png');