🔧 config(lint): Upgrade xo.

Author: make-github-pseudonymous-again

doc/scripts/header.js

@@ -1,34 +1,31 @@
-var domReady = function(callback) {
-	var state = document.readyState ;
-    if ( state === 'interactive' || state === 'complete' ) {
-		callback() ;
-	}
-	else {
+const domReady = function (callback) {
+	const state = document.readyState;
+	if (state === 'interactive' || state === 'complete') {
+		callback();
+	} else {
 		document.addEventListener('DOMContentLoaded', callback);
 	}
-} ;
-
+};
 
-domReady(function(){
-
-	var projectname = document.createElement('a');
+domReady(() => {
+	const projectname = document.createElement('a');
 	projectname.classList.add('project-name');
 	projectname.text = 'comparison-sorting/insertion-sort';
-	projectname.href = './index.html' ;
+	projectname.href = './index.html';
 
-	var header = document.getElementsByTagName('header')[0] ;
-	header.insertBefore(projectname,header.firstChild);
+	const header = document.querySelectorAll('header')[0];
+	header.insertBefore(projectname, header.firstChild);
 
-	var testlink = document.querySelector('header > a[data-ice="testLink"]') ;
-	testlink.href = 'https://coveralls.io/github/comparison-sorting/insertion-sort' ;
-	testlink.target = '_BLANK' ;
+	const testlink = document.querySelector('header > a[data-ice="testLink"]');
+	testlink.href =
+		'https://coveralls.io/github/comparison-sorting/insertion-sort';
+	testlink.target = '_BLANK';
 
-	var searchBox = document.querySelector('.search-box');
-	var input = document.querySelector('.search-input');
+	const searchBox = document.querySelector('.search-box');
+	const input = document.querySelector('.search-input');
 
-	// active search box when focus on searchBox.
-	input.addEventListener('focus', function(){
+	// Active search box when focus on searchBox.
+	input.addEventListener('focus', () => {
 		searchBox.classList.add('active');
 	});
-
 });

package.json

@@ -89,7 +89,7 @@
     "pinst": "2.1.6",
     "power-assert": "1.6.1",
     "regenerator-runtime": "0.13.7",
-    "xo": "0.36.1"
+    "xo": "0.42.0"
   },
   "ava": {
     "files": [
@@ -194,12 +194,21 @@
       "unicorn"
     ],
     "rules": {
+      "unicorn/prefer-node-protocol": "off",
       "unicorn/filename-case": [
         "error",
         {
           "case": "camelCase"
         }
       ]
-    }
+    },
+    "overrides": [
+      {
+        "files": [
+          "doc/**"
+        ],
+        "env": "browser"
+      }
+    ]
   }
 }