use const and template literal

[BREAKING] drop support for Node < 4

index.js

@@ -4,19 +4,19 @@
 */
 'use strict';
 
-var validateGlobOpts = require('validate-glob-opts');
+const validateGlobOpts = require('validate-glob-opts');
 
 function isTypeError(err) {
   return err.name === 'TypeError';
 }
 
 function createMessageLine(msg, err, index) {
-  return msg + '\n  ' + (index + 1) + '. ' + err.message;
+  return `${msg}\n  ${index + 1}. ${err.message}`;
 }
 
 module.exports = function assertValidGlobOpts(obj) {
-  var results = validateGlobOpts(obj);
-  var count = results.length;
+  const results = validateGlobOpts(obj);
+  const count = results.length;
 
   if (count === 0) {
     return;
@@ -28,6 +28,6 @@ module.exports = function assertValidGlobOpts(obj) {
 
   throw new (results.every(isTypeError) ? TypeError : Error)(results.reduce(
     createMessageLine,
-    String(count) + ' errors found in the node-glob options:'
+    `${count} errors found in the node-glob options:`
   ));
 };

package.json

@@ -30,12 +30,12 @@
     "validate-glob-opts": "^0.2.0"
   },
   "devDependencies": {
-    "@shinnn/eslint-config-node-legacy": "^3.0.0",
-    "eslint": "^3.14.0",
+    "@shinnn/eslint-config-node": "^3.0.0",
+    "eslint": "^3.16.1",
     "istanbul": "^0.4.5",
     "tape": "^4.6.3"
   },
   "eslintConfig": {
-    "extends": "@shinnn/node-legacy"
+    "extends": "@shinnn/node"
   }
 }