use jshint to lint

Author: HandsomeOne

.gitattributes

@@ -0,0 +1,11 @@
+{
+  "esversion": 5,
+  "browser": true,
+  "strict": "global",
+  "unused": true,
+  "undef": true,
+  "curly": true,
+  "eqeqeq": true,
+  "forin": true,
+  "devel": true
+}

.jshintrc

@@ -1,4 +1,6 @@
+'use strict';
 var i18n = {};
+/* jshint -W069 */
 i18n['en'] = {
   won: "won",
   total: "total",
@@ -9,7 +11,7 @@ i18n['en'] = {
   rule2: "Each of the four given numerical digits <b>must appear once</b>, and <b>no other</b> digits are allowed.",
   rule3: "Besides digits, <b>only</b> these operators are allowed: <code>+</code> <code>-</code> <code>*</code> <code>/</code> <code>%</code> <code>~</code> <code>&amp;</code> <code>|</code> <code>^</code> <code>&lt;&lt;</code> <code>&gt;&gt;</code> <code>(</code> <code>)</code> and <code>x</code>(after a given <code>0</code>).",
   rule4: "In additional, to avoid <code>-~</code> from appearing continuously, <code>-</code> is <b>not allowed</b> to be used as a unary operator.",
-}
+};
 i18n['zh-CN'] = {
   won: "已获胜",
   total: "总局数",

js/i18n.js

@@ -1,3 +1,4 @@
+'use strict';
 function $(selector) {
   return document.querySelector(selector);
 }
@@ -45,6 +46,7 @@ $('#expr').addEventListener('input', function() {
       return;
     default:
       try {
+        /* jshint -W061 */
         var result = eval($('#expr').value);
         if (result === null) {
           $('#result').innerHTML = 'null';
@@ -63,7 +65,7 @@ function check(result) {
   var expr = $('#expr').value;
   var e = expr.replace(/(\d|\))-/g, /$1/).replace(/&&|\|\|/g, '#').replace(/>>|<<|[+*\/%~^&|()]/g, '').replace(/0x/ig, '0');
   var digitsAppeared = 0;
-  for (i = 0; i < 4; i++) {
+  for (var i = 0; i < 4; i++) {
     if (e.match(localStorage.digits[i])) {
       e = e.replace(localStorage.digits[i], '');
       digitsAppeared += 1;
@@ -101,7 +103,7 @@ function success() {
   $('#solution').className = 'animate';
   $('#solution').innerHTML = ' = ' + $('#expr').value;
   $('#expr').setAttribute('disabled', '');
-  setTimeout(function(params) {
+  setTimeout(function() {
     printStats();
     $('#stats').className = 'hover';
   }, 250);