Configring node js.

node_modules/core-js/modules/_classof.js

@@ -0,0 +1,23 @@
+// getting tag from 19.1.3.6 Object.prototype.toString()
+var cof = require('./_cof')
+  , TAG = require('./_wks')('toStringTag')
+  // ES3 wrong here
+  , ARG = cof(function(){ return arguments; }()) == 'Arguments';
+
+// fallback for IE11 Script Access Denied error
+var tryGet = function(it, key){
+  try {
+    return it[key];
+  } catch(e){ /* empty */ }
+};
+
+module.exports = function(it){
+  var O, T, B;
+  return it === undefined ? 'Undefined' : it === null ? 'Null'
+    // @@toStringTag case
+    : typeof (T = tryGet(O = Object(it), TAG)) == 'string' ? T
+    // builtinTag case
+    : ARG ? cof(O)
+    // ES3 arguments fallback
+    : (B = cof(O)) == 'Object' && typeof O.callee == 'function' ? 'Arguments' : B;
+};