Use const, let.

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

.eslintrc.js

@@ -1,11 +1,14 @@
 module.exports = {
     "env": {
       "browser": false,
-      "es6": false,
+      "es6": true,
       "mocha": true,
       "node": true
     },
-    "extends": "google",
+    "extends": [
+      "google",
+      "eslint:recommended"
+    ],
     "rules": {
       "block-spacing": [2, "always"],
       "brace-style": [2, "1tbs", { "allowSingleLine": true }],
@@ -14,6 +17,8 @@ module.exports = {
       "curly": 0,
       "key-spacing": [2, {align: "value"}],
       "max-len": [1, 120],
+      "no-console": 1,
+      "no-empty": [2, { "allowEmptyCatch": true }],
       "no-eval": 1, // we use it on purpose
       "no-loop-func": 1,
       "no-multi-spaces": 0,

lib/cache.js

@@ -4,28 +4,27 @@ var path = require('path');
 
 var h = require('./helper');
 
-var cache = {};
+const cache = {};
 
 cache.init = function() {
   h.mkdir(h.getCacheDir());
 };
 
 cache.get = function(k) {
-  var fullpath = h.getCacheFile(k);
+  const fullpath = h.getCacheFile(k);
   if (!fs.existsSync(fullpath)) return null;
 
-  var v = JSON.parse(fs.readFileSync(fullpath));
-  return v;
+  return JSON.parse(fs.readFileSync(fullpath));
 };
 
 cache.set = function(k, v) {
-  var fullpath = h.getCacheFile(k);
+  const fullpath = h.getCacheFile(k);
   fs.writeFileSync(fullpath, JSON.stringify(v));
   return true;
 };
 
 cache.del = function(k) {
-  var fullpath = h.getCacheFile(k);
+  const fullpath = h.getCacheFile(k);
   if (!fs.existsSync(fullpath)) return false;
 
   fs.unlinkSync(fullpath);
@@ -38,8 +37,8 @@ cache.list = function() {
       return path.extname(filename) === '.json';
     })
     .map(function(filename) {
-      var k = path.basename(filename, '.json');
-      var stat = fs.statSync(h.getCacheFile(k));
+      const k = path.basename(filename, '.json');
+      const stat = fs.statSync(h.getCacheFile(k));
       return {
         name:  k,
         size:  stat.size,

lib/chalk.js

@@ -3,17 +3,17 @@ var _ = require('underscore');
 var style = require('ansi-styles');
 var supportsColor = require('supports-color');
 
-var chalk = {
+const chalk = {
   enabled: supportsColor.stdout,
   use256:  supportsColor.stdout && supportsColor.stdout.has256,
   themes:  {},
   theme:   {}
 };
 
-var pres = [];
-var posts = [];
+const pres = [];
+const posts = [];
 
-var DEFAULT = {
+const DEFAULT = {
   black:   '#000000',
   blue:    '#0000ff',
   cyan:    '#00ffff',
@@ -26,12 +26,12 @@ var DEFAULT = {
 };
 
 chalk.setTheme = function(name) {
-  var theme = this.themes[name] || this.themes.default || {};
+  const theme = this.themes[name] || this.themes.default || {};
   this.theme = _.extendOwn(DEFAULT, theme);
 };
 
 chalk.sprint = function(s, hex) {
-  var color = chalk.use256 ? style.color.ansi256.hex(hex) : style.color.ansi.hex(hex);
+  const color = chalk.use256 ? style.color.ansi256.hex(hex) : style.color.ansi.hex(hex);
   return color + s + style.color.close;
 };
 
@@ -44,9 +44,7 @@ chalk.print = function(s) {
 chalk.wrap = function(pre, post) {
   pres.push(pre);
   posts.unshift(post);
-  var f = function(s) {
-    return chalk.print(s);
-  };
+  const f = function(s) { return chalk.print(s); };
   Object.setPrototypeOf(f, chalk);
   return f;
 };
@@ -55,11 +53,11 @@ function bgName(s) { return 'bg' + s[0].toUpperCase() + s.substr(1); }
 
 chalk.init = function() {
   require('./helper').getCodeDirData('colors').forEach(function(f) {
-    var o = {};
+    const o = {};
     _.pairs(f.data).forEach(function(x) {
-      var k = x[0];
-      var v = x[1];
-      var bgK = bgName(k);
+      const k = x[0];
+      const v = x[1];
+      const bgK = bgName(k);
 
       if (chalk.use256) {
         o[k] = style.color.ansi256.hex(v);
@@ -80,7 +78,7 @@ chalk.init = function() {
       },
       configurable: true
     });
-    var bgcolor = bgName(color);
+    const bgcolor = bgName(color);
     Object.defineProperty(chalk, bgcolor, {
       get: function() {
         return chalk.wrap(chalk.theme[bgcolor], style.bgColor.close);

lib/cli.js

@@ -27,24 +27,22 @@ function initIcon() {
 function initLogLevel() {
   log.init();
 
-  var level = 'INFO';
+  let level = 'INFO';
   if (process.argv.indexOf('-v') >= 0) level = 'DEBUG';
   if (process.argv.indexOf('-vv') >= 0) level = 'TRACE';
 
   // print HTTP details in TRACE
   if (level === 'TRACE') {
-    var request = require('request');
+    const request = require('request');
     request.debug = true;
 
     console.error = _.wrap(console.error, function(func) {
-      var args = _.toArray(arguments);
+      let args = _.toArray(arguments);
       args.shift();
 
       // FIXME: hack HTTP request log, hope no one else use it...
       if (args.length > 0 && args[0].indexOf('REQUEST ') === 0) {
-        args = args.map(function(arg) {
-          return h.printSafeHTTP(arg);
-        });
+        args = args.map(function(arg) { return h.printSafeHTTP(arg); });
         log.trace.apply(log, args);
       } else {
         log.info.apply(log, args);

lib/commands/cache.js

@@ -7,7 +7,7 @@ var log = require('../log');
 var cache = require('../cache');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'cache [keyword]',
   desc:    'Manage local cache',
   builder: function(yargs) {
@@ -33,7 +33,7 @@ var cmd = {
 cmd.handler = function(argv) {
   session.argv = argv;
 
-  var caches = cache.list()
+  const caches = cache.list()
     .filter(function(f) {
       return argv.keyword.length === 0 || f.name.startsWith(argv.keyword + '.');
     });
@@ -42,7 +42,7 @@ cmd.handler = function(argv) {
     caches.forEach(function(f) { cache.del(f.name); });
   } else {
     _.sortBy(caches, function(f) {
-      var x = parseInt(f.name.split('.')[0], 10);
+      let x = parseInt(f.name.split('.')[0], 10);
       if (Number.isNaN(x)) x = 0;
       return x;
     })

lib/commands/config.js

@@ -8,7 +8,7 @@ var config = require('../config');
 var log = require('../log');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'config [key] [value]',
   aliases: ['conf', 'cfg', 'setting'],
   desc:    'Manage user configs',
@@ -49,7 +49,7 @@ function prettyConfig(cfg) {
 }
 
 function loadConfig(showall) {
-  var cfg = showall ? config.getAll(true) : nconf.get();
+  const cfg = showall ? config.getAll(true) : nconf.get();
   return _.omit(cfg, 'type');
 }
 
@@ -65,7 +65,7 @@ cmd.handler = function(argv) {
   if (argv.key.length === 0)
     return log.info(prettyConfig(loadConfig(argv.all)));
 
-  var v = nconf.get(argv.key);
+  const v = nconf.get(argv.key);
 
   // delete
   if (argv.delete) {

lib/commands/list.js

@@ -9,7 +9,7 @@ var log = require('../log');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'list [keyword]',
   aliases: ['ls'],
   desc:    'List questions',
@@ -47,7 +47,7 @@ cmd.handler = function(argv) {
   core.filterProblems(argv, function(e, problems) {
     if (e) return log.fail(e);
 
-    var word = argv.keyword.toLowerCase();
+    const word = argv.keyword.toLowerCase();
     if (word) {
       if (word.endsWith(word.substr(-1).repeat(6))) {
         log.warn('Hmmm...you might need a new keyboard?');
@@ -57,8 +57,8 @@ cmd.handler = function(argv) {
       });
     }
 
-    var stat = {};
-    var KEYS = ['locked', 'starred', 'ac', 'notac', 'None', 'Easy', 'Medium', 'Hard'];
+    const stat = {};
+    const KEYS = ['locked', 'starred', 'ac', 'notac', 'None', 'Easy', 'Medium', 'Hard'];
     KEYS.forEach(function(x) { stat[x] = 0; });
 
     problems = _.sortBy(problems, function(x) { return -x.id; });
@@ -78,12 +78,12 @@ cmd.handler = function(argv) {
           problem.percent);
 
       if (argv.extra) {
-        var badges = [problem.category];
+        let badges = [problem.category];
         badges = badges.concat(problem.companies || []);
         badges = badges.concat(problem.tags || []);
 
-        var buf = [];
-        var len = 0;
+        let buf = [];
+        let len = 0;
         badges.forEach(function(x) {
           if (len + x.length + 3 >= 60) {
             log.printf('%12s%s', ' ', chalk.dim(buf.join(' | ')));

lib/commands/plugin.js

@@ -8,7 +8,7 @@ var log = require('../log');
 var Plugin = require('../plugin');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'plugin [name]',
   aliases: ['extension', 'ext'],
   desc:    'Manage plugins',
@@ -62,7 +62,7 @@ var cmd = {
 cmd.handler = function(argv) {
   session.argv = argv;
 
-  var name = argv.name;
+  const name = argv.name;
   if (argv.install) {
     Plugin.install(name, function(e, plugin) {
       if (e) return log.error(e);
@@ -71,28 +71,27 @@ cmd.handler = function(argv) {
     return;
   }
 
-  var plugins = Plugin.plugins;
+  let plugins = Plugin.plugins;
   if (name) {
     plugins = plugins.filter(function(p) {
       return p.name === name;
     });
   }
   if (plugins.length === 0) return log.error('Plugin not found!');
 
-  var plugin = plugins[0];
-  var fullpath = h.getPluginFile(plugin.file);
-  var newname;
+  const plugin = plugins[0];
+  const fullpath = h.getPluginFile(plugin.file);
 
   if (argv.enable) {
     if (plugin.enabled) return;
-    newname = h.getPluginFile(plugin.file.substr(1));
+    const newname = h.getPluginFile(plugin.file.substr(1));
 
     fs.rename(fullpath, newname, function(e) {
       if (e) log.error(e.message);
     });
   } else if (argv.disable) {
     if (!plugin.enabled) return;
-    newname = h.getPluginFile('.' + plugin.file);
+    const newname = h.getPluginFile('.' + plugin.file);
 
     fs.rename(fullpath, newname, function(e) {
       if (e) log.error(e.message);

lib/commands/show.js

@@ -13,7 +13,7 @@ var config = require('../config');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'show [keyword]',
   aliases: ['view', 'pull'],
   desc:    'Show question',
@@ -68,28 +68,28 @@ var cmd = {
 
 function genFileName(problem, lang) {
   // try to use a new filename to avoid overwrite by mistake
-  var name = problem.id + '.' + problem.slug + h.langToExt(lang);
-  var i = 0;
+  let name = problem.id + '.' + problem.slug + h.langToExt(lang);
+  let i = 0;
   while (fs.existsSync(name))
     name = problem.id + '.' + problem.slug + '.' + (i++) + h.langToExt(lang);
   return name;
 }
 
 function showProblem(problem, argv) {
-  var taglist = [problem.category]
+  const taglist = [problem.category]
     .concat(problem.companies || [])
     .concat(problem.tags || [])
     .map(function(x) { return h.badge(x, 'blue'); })
     .join(' ');
-  var langlist = problem.templates
+  const langlist = problem.templates
     .map(function(x) { return h.badge(x.value, 'yellow'); })
     .sort()
     .join(' ');
 
-  var code;
-  var needcode = argv.gen || argv.codeonly;
+  let code;
+  const needcode = argv.gen || argv.codeonly;
   if (needcode) {
-    var template = problem.templates.find(function(x) {
+    const template = problem.templates.find(function(x) {
       return x.value === argv.lang;
     });
     if (!template) {
@@ -98,15 +98,15 @@ function showProblem(problem, argv) {
       return;
     }
 
-    var opts = {
+    const opts = {
       lang: argv.lang,
       code: template.defaultCode,
       tpl:  argv.extra ? 'detailed' : 'codeonly'
     };
     code = core.exportProblem(problem, opts);
   }
 
-  var filename;
+  let filename;
   if (argv.gen) {
     filename = genFileName(problem, argv.lang);
     fs.writeFileSync(filename, code);
@@ -166,15 +166,15 @@ cmd.handler = function(argv) {
       if (e) return log.fail(e);
 
       // random select one that not AC-ed yet
-      var user = session.getUser();
+      const user = session.getUser();
       problems = problems.filter(function(x) {
         if (x.state === 'ac') return false;
         if (!user.paid && x.locked) return false;
         return true;
       });
-      if (problems.length === 0) return cb('Problem not found!');
+      if (problems.length === 0) return log.fail('Problem not found!');
 
-      var problem = _.sample(problems);
+      const problem = _.sample(problems);
       core.getProblem(problem, function(e, problem) {
         if (e) return log.fail(e);
         showProblem(problem, argv);

lib/commands/star.js

@@ -5,7 +5,7 @@ var log = require('../log');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'star <keyword>',
   aliases: ['like', 'favorite'],
   desc:    'Star favorite question',

lib/commands/stat.js

@@ -9,7 +9,7 @@ var core = require('../core');
 var session = require('../session');
 var h = require('../helper');
 
-var cmd = {
+const cmd = {
   command: 'stat',
   desc:    'Show statistics',
   aliases: ['stats', 'progress', 'report'],
@@ -51,25 +51,25 @@ function bar(c, n) {
 }
 
 function printLine(key, done, all) {
-  var n = 30;
-  var percent = (all > 0) ? done / all : 0;
-  var x = Math.ceil(n * percent);
+  const n = 30;
+  const percent = (all > 0) ? done / all : 0;
+  const x = Math.ceil(n * percent);
   log.printf(' %s\t%3d/%-3d (%.2f%%)  %s%s',
       h.prettyLevel(key), done, all, 100 * percent,
       chalk.green(bar('█', x)),
       chalk.red(bar('░', n - x)));
 }
 
 function showProgress(problems) {
-  var stats = {
+  const stats = {
     easy:   {all: 0, ac: 0},
     medium: {all: 0, ac: 0},
     hard:   {all: 0, ac: 0}
   };
 
   problems.forEach(function(problem) {
-    var level = problem.level.toLowerCase();
-    var state = problem.state.toLowerCase();
+    const level = problem.level.toLowerCase();
+    const state = problem.state.toLowerCase();
 
     if (!(level in stats)) return;
     ++stats[level].all;
@@ -83,14 +83,14 @@ function showProgress(problems) {
   printLine('Hard', stats.hard.ac, stats.hard.all);
 }
 
-var CHARS = {
+const CHARS = {
   ac:    h.isWindows() ? 'O ' : '▣ ',
   notac: h.isWindows() ? 'X ' : '▤ ',
   none:  h.isWindows() ? 'o ' : '⬚ ',
 };
 
 function showGraph(problems) {
-  var ICONS = {
+  const ICONS = {
     ac:    chalk.green(CHARS.ac),
     notac: chalk.red(CHARS.notac),
     none:  chalk.gray(CHARS.none),
@@ -100,22 +100,22 @@ function showGraph(problems) {
   // row header is 4 bytes
   // each question takes 2 bytes
   // each group has 10 questions, which takes (2*10=20) + 3 paddings
-  var groups = Math.floor((h.width - 4) / (3 + 2 * 10));
+  let groups = Math.floor((h.width - 4) / (3 + 2 * 10));
   if (groups < 1) groups = 1;
   if (groups > 5) groups = 5;
 
-  var header = _.range(groups)
+  const header = _.range(groups)
     .map(function(x) { return sprintf('%5d%18d', x * 10 + 1, x * 10 + 10); })
     .join('');
   log.info('    ' + header);
 
-  var graph = [];
+  const graph = [];
   problems.forEach(function(problem) {
     graph[problem.id] = ICONS[problem.state] || ICONS.none;
   });
 
-  var line = [sprintf(' %03d', 0)];
-  for (var i = 1, n = graph.length; i <= n; ++i) {
+  let line = [sprintf(' %03d', 0)];
+  for (let i = 1, n = graph.length; i <= n; ++i) {
     // padding before group
     if (i % 10 === 1) line.push('   ');
 
@@ -136,64 +136,63 @@ function showGraph(problems) {
 }
 
 function showCal() {
-  var MONTHS = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
-  var WEEKDAYS = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
-  var ICONS = [
+  const MONTHS = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
+  const WEEKDAYS = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
+  const ICONS = [
     CHARS.none,
     chalk.sprint(CHARS.ac, '#ffffcc'),
     chalk.sprint(CHARS.ac, '#ccff66'),
     chalk.sprint(CHARS.ac, '#66cc33'),
     chalk.sprint(CHARS.ac, '#00ff00')
   ];
 
-  var N_MONTHS = 12;
-  var N_WEEKS = 53;
-  var N_WEEKDAYS = 7;
+  const N_MONTHS = 12;
+  const N_WEEKS = 53;
+  const N_WEEKDAYS = 7;
 
-  var now = moment();
+  const now = moment();
 
   // load historical stats
-  var graph = [];
-  var stats = require('../cache').get(h.KEYS.stat) || {};
+  const graph = [];
+  const stats = require('../cache').get(h.KEYS.stat) || {};
   _.keys(stats).forEach(function(k) {
-    var v = stats[k].ac || 0;
+    const v = stats[k].ac || 0;
     if (v === 0) return;
 
-    var d = moment(k, 'YYYY-MM-DD');
+    const d = moment(k, 'YYYY-MM-DD');
     graph[now.diff(d, 'days')] = v;
   });
 
   // print header
-  var buf = Buffer.alloc(120, ' ', 'ascii');
-  for (var i = 0; i <= N_MONTHS; ++i) {
+  const buf = Buffer.alloc(120, ' ', 'ascii');
+  for (let i = 0; i <= N_MONTHS; ++i) {
     // for day 1 in each month, calculate its column position in graph
-    var d = now.clone().subtract(i, 'months').date(1);
-    var idx = now.diff(d, 'days');
+    const d = now.clone().subtract(i, 'months').date(1);
+    const idx = now.diff(d, 'days');
 
-    var j = (N_WEEKS - idx / N_WEEKDAYS + 1) * 2;
+    const j = (N_WEEKS - idx / N_WEEKDAYS + 1) * 2;
     if (j >= 0) buf.write(MONTHS[d.month()], j);
   }
   log.printf('%7s%s', ' ', buf.toString());
 
   // print graph
-  var idx;
-  for (var i = 0; i < N_WEEKDAYS; ++i) {
-    var line = [];
+  for (let i = 0; i < N_WEEKDAYS; ++i) {
+    const line = [];
     // print day in week
-    idx = (now.day() + i + 1) % N_WEEKDAYS;
+    const idx = (now.day() + i + 1) % N_WEEKDAYS;
     line.push(sprintf('%4s   ', WEEKDAYS[idx]));
 
-    for (var j = 0; j < N_WEEKS; ++j) {
-      idx = (N_WEEKS - j - 1) * N_WEEKDAYS + N_WEEKDAYS - i - 1;
-      var d = now.clone().subtract(idx, 'days');
+    for (let j = 0; j < N_WEEKS; ++j) {
+      let idx = (N_WEEKS - j - 1) * N_WEEKDAYS + N_WEEKDAYS - i - 1;
+      const d = now.clone().subtract(idx, 'days');
 
       // map count to icons index:
       // [0] => 0, [1,5] => 1, [6,10] => 2, [11,15] => 3, [16,) => 4
-      var count = graph[idx] || 0;
+      const count = graph[idx] || 0;
       idx = Math.floor((count - 1) / 5) + 1;
       if (idx > 4) idx = 4;
 
-      var icon = ICONS[idx];
+      let icon = ICONS[idx];
       // use different colors for adjacent months
       if (idx === 0 && d.month() % 2) icon = chalk.gray(icon);
       line.push(icon);

lib/commands/submission.js

@@ -10,7 +10,7 @@ var Queue = require('../queue');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'submission [keyword]',
   desc:    'Download submission code',
   builder: function(yargs) {
@@ -50,7 +50,7 @@ var cmd = {
 };
 
 function doTask(problem, queue, cb) {
-  var argv = queue.ctx.argv;
+  const argv = queue.ctx.argv;
 
   function onTaskDone(e, msg) {
     // NOTE: msg color means different purpose:
@@ -66,7 +66,7 @@ function doTask(problem, queue, cb) {
   if (argv.extra) {
     // have to get problem details, e.g. problem description.
     core.getProblem(problem.id, function(e, problem) {
-      if (e) return done(e);
+      if (e) return cb(e);
       exportSubmission(problem, argv, onTaskDone);
     });
   } else {
@@ -88,12 +88,12 @@ function exportSubmission(problem, argv, cb) {
       return cb('No submissions in required language.');
 
     // if no accepted, use the latest non-accepted one
-    var submission = submissions.find(function(x) {
+    const submission = submissions.find(function(x) {
       return x.status_display === 'Accepted';
     }) || submissions[0];
     submission.ac = (submission.status_display === 'Accepted');
 
-    var f = sprintf('%s/%d.%s.%s.%s%s',
+    const f = sprintf('%s/%d.%s.%s.%s%s',
         argv.outdir,
         problem.id,
         problem.slug,
@@ -109,7 +109,7 @@ function exportSubmission(problem, argv, cb) {
     core.getSubmission(submission, function(e, submission) {
       if (e) return cb(e);
 
-      var opts = {
+      const opts = {
         lang: submission.lang,
         code: submission.code,
         tpl:  argv.extra ? 'detailed' : 'codeonly'
@@ -123,7 +123,7 @@ function exportSubmission(problem, argv, cb) {
 
 cmd.handler = function(argv) {
   session.argv = argv;
-  var q = new Queue(null, {argv: argv}, doTask);
+  const q = new Queue(null, {argv: argv}, doTask);
 
   if (argv.all) {
     core.getProblems(function(e, problems) {

lib/commands/submit.js

@@ -10,7 +10,7 @@ var log = require('../log');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'submit <filename>',
   aliases: ['push', 'commit'],
   desc:    'Submit code',
@@ -28,18 +28,18 @@ var cmd = {
 function printResult(actual, k) {
   if (!actual.hasOwnProperty(k)) return;
 
-  var v = actual[k] || '';
-  var lines = Array.isArray(v) ? v : [v];
+  const v = actual[k] || '';
+  const lines = Array.isArray(v) ? v : [v];
   lines.forEach(function(line) {
     if (k !== 'state') line = k + ': ' + line;
     log.info('  ' + h.prettyText(' ' + line, actual.ok));
   });
 }
 
 function printLine() {
-  var args = _.toArray(arguments);
-  var actual = args.shift();
-  var line = util.format.apply(util, args);
+  const args = _.toArray(arguments);
+  const actual = args.shift();
+  const line = util.format.apply(util, args);
   log.info('  ' + h.prettyText(' ' + line, actual.ok));
 }
 
@@ -50,7 +50,7 @@ cmd.handler = function(argv) {
 
   // use the 1st section in filename as keyword
   // e.g. two-sum.cpp, or two-sum.78502271.ac.cpp
-  var keyword = h.getFilename(argv.filename).split('.')[0];
+  const keyword = h.getFilename(argv.filename).split('.')[0];
 
   core.getProblem(keyword, function(e, problem) {
     if (e) return log.fail(e);
@@ -60,7 +60,7 @@ cmd.handler = function(argv) {
     core.submitProblem(problem, function(e, results) {
       if (e) return log.fail(e);
 
-      var result = results[0];
+      const result = results[0];
 
       printResult(result, 'state');
       printLine(result, '%d/%d cases passed (%s)',
@@ -72,11 +72,11 @@ cmd.handler = function(argv) {
           if (e || !submission || !submission.distributionChart)
             return log.warn('Failed to get submission beat ratio.');
 
-          var lang = submission.distributionChart.lang;
-          var scores = submission.distributionChart.distribution;
-          var myRuntime = parseFloat(result.runtime);
+          const lang = submission.distributionChart.lang;
+          const scores = submission.distributionChart.distribution;
+          const myRuntime = parseFloat(result.runtime);
 
-          var ratio = 0.0;
+          let ratio = 0.0;
           scores.forEach(function(score) {
             if (parseFloat(score[0]) > myRuntime)
               ratio += parseFloat(score[1]);

lib/commands/test.js

@@ -8,7 +8,7 @@ var log = require('../log');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'test <filename>',
   aliases: ['run'],
   desc:    'Test code',
@@ -39,13 +39,13 @@ var cmd = {
 function printResult(actual, expect, k) {
   if (!actual.hasOwnProperty(k)) return;
   // HACk: leetcode still return 'Accepted' even the answer is wrong!!
-  var v = actual[k] || '';
+  const v = actual[k] || '';
   if (k === 'state' && v === 'Accepted') return;
 
-  var ok = actual.ok;
+  let ok = actual.ok;
   if (expect && !_.isEqual(actual[k], expect[k])) ok = false;
 
-  var lines = Array.isArray(v) ? v : [v];
+  const lines = Array.isArray(v) ? v : [v];
   lines.forEach(function(line) {
     if (k !== 'state') line = k + ': ' + line;
     log.info('  ' + h.prettyText(' ' + line, ok));
@@ -58,7 +58,7 @@ function runTest(argv) {
 
   // use the 1st section in filename as keyword
   // e.g. two-sum.cpp, or two-sum.78502271.ac.cpp
-  var keyword = h.getFilename(argv.filename).split('.')[0];
+  const keyword = h.getFilename(argv.filename).split('.')[0];
 
   core.getProblem(keyword, function(e, problem) {
     if (e) return log.fail(e);
@@ -80,7 +80,7 @@ function runTest(argv) {
     core.testProblem(problem, function(e, results) {
       if (e) return log.fail(e);
 
-      for (var i = 0; i < results.length; ++i) {
+      for (let i = 0; i < results.length; ++i) {
         log.info();
         log.info(chalk.yellow(results[i].type));
 

lib/commands/user.js

@@ -6,7 +6,7 @@ var log = require('../log');
 var core = require('../core');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'user',
   desc:    'Manage account',
   builder: function(yargs) {
@@ -30,7 +30,7 @@ var cmd = {
 
 cmd.handler = function(argv) {
   session.argv = argv;
-  var user = null;
+  let user = null;
   if (argv.login) {
     // login
     prompt.colors = false;

lib/commands/version.js

@@ -7,7 +7,7 @@ var log = require('../log');
 var Plugin = require('../plugin');
 var session = require('../session');
 
-var cmd = {
+const cmd = {
   command: 'version',
   aliases: ['info', 'env'],
   desc:    'Show version info',
@@ -23,10 +23,10 @@ function printLine(k, v) {
 }
 
 function getVersion() {
-  var version = require('../../package.json').version;
+  let version = require('../../package.json').version;
 
   try {
-    var commit = require('../../.env.json').commit.short;
+    const commit = require('../../.env.json').commit.short;
     if (commit) version += '-' + commit;
   } catch (e) {}
 
@@ -35,12 +35,12 @@ function getVersion() {
 
 cmd.handler = function(argv) {
   session.argv = argv;
-  var version = getVersion();
+  const version = getVersion();
 
   if (!log.isEnabled('DEBUG'))
     return log.info(version);
 
-  var logo = [
+  const logo = [
     ' _           _                  _      ',
     '| |         | |                | |     ',
     '| | ___  ___| |_  ___  ___   __| | ___ ',
@@ -50,9 +50,9 @@ cmd.handler = function(argv) {
   ].join('\n');
   log.info(logo);
 
-  var h = require('../helper');
-  var os = require('os');
-  var config = require('../config');
+  const h = require('../helper');
+  const os = require('os');
+  const config = require('../config');
 
   log.info('\n[Environment]');
   printLine('Node', process.version);

lib/config.js

@@ -4,7 +4,7 @@ var nconf = require('nconf');
 
 var h = require('./helper');
 
-var DEFAULT_CONFIG = {
+const DEFAULT_CONFIG = {
   // usually you don't wanna change those
   sys: {
     categories: [
@@ -73,12 +73,12 @@ Config.prototype.init = function() {
     .add('global', {type: 'literal', store: DEFAULT_CONFIG})
     .defaults({});
 
-  var cfg = nconf.get();
+  const cfg = nconf.get();
   nconf.remove('local');
   nconf.remove('global');
 
   // HACK: remove old style configs
-  for (var x in cfg) {
+  for (let x in cfg) {
     if (x === x.toUpperCase()) delete cfg[x];
   }
   delete DEFAULT_CONFIG.type;
@@ -88,7 +88,7 @@ Config.prototype.init = function() {
 };
 
 Config.prototype.getAll = function(useronly) {
-  var cfg = _.extendOwn({}, this);
+  const cfg = _.extendOwn({}, this);
   if (useronly) delete cfg.sys;
   return cfg;
 };

lib/core.js

@@ -8,7 +8,7 @@ var log = require('./log');
 var h = require('./helper');
 var Plugin = require('./plugin');
 
-var core = new Plugin(99999999, 'core', '20170722', 'Plugins manager');
+const core = new Plugin(99999999, 'core', '20170722', 'Plugins manager');
 
 core.filters = {
   query: {
@@ -44,7 +44,7 @@ function isACed(x) { return x.state === 'ac'; }
 function isLocked(x) { return x.locked; }
 function isStarred(x) { return x.starred; }
 
-var QUERY_HANDLERS = {
+const QUERY_HANDLERS = {
   e: isLevel,
   E: _.negate(isLevel),
   m: isLevel,
@@ -64,7 +64,7 @@ core.filterProblems = function(opts, cb) {
     if (e) return cb(e);
 
     (opts.query || '').split('').forEach(function(q) {
-      var f = QUERY_HANDLERS[q];
+      const f = QUERY_HANDLERS[q];
       if (!f) return;
       problems = problems.filter(function(x) { return f(x, q); });
     });
@@ -89,7 +89,7 @@ core.getProblem = function(keyword, cb) {
     if (e) return cb(e);
 
     keyword = Number(keyword) || keyword;
-    var problem = problems.find(function(x) {
+    const problem = problems.find(function(x) {
       return x.id === keyword || x.name === keyword || x.slug === keyword;
     });
     if (!problem) return cb('Problem not found!');
@@ -108,7 +108,7 @@ core.starProblem = function(problem, starred, cb) {
 
 core.exportProblem = function(problem, opts) {
   // copy problem attrs thus we can render it in template
-  var input = _.extend({}, problem);
+  const input = _.extend({}, problem);
 
   input.code = opts.code.replace(/\r\n/g, '\n');
   input.comment = h.langToCommentStyle(opts.lang);
@@ -118,13 +118,13 @@ core.exportProblem = function(problem, opts) {
   if (opts.tpl === 'detailed') {
     // NOTE: wordwrap internally uses '\n' as EOL, so here we have to
     // remove all '\r' in the raw string.
-    var desc = input.desc.replace(/\r\n/g, '\n').replace(/^ /mg, '⁠');
-    var wrap = require('wordwrap')(79 - input.comment.line.length);
+    const desc = input.desc.replace(/\r\n/g, '\n').replace(/^ /mg, '⁠');
+    const wrap = require('wordwrap')(79 - input.comment.line.length);
     input.desc = wrap(desc).split('\n');
   }
 
-  var tplfile = path.join(h.getCodeDir('templates'), opts.tpl + '.tpl');
-  var output = _.template(h.getFileData(tplfile))(input);
+  const tplfile = path.join(h.getCodeDir('templates'), opts.tpl + '.tpl');
+  let output = _.template(h.getFileData(tplfile))(input);
 
   if (h.isWindows()) {
     output = output.replace(/\n/g, '\r\n');

lib/helper.js

@@ -6,14 +6,14 @@ var _ = require('underscore');
 var mkdirp = require('mkdirp');
 var ora = require('ora');
 
-var UNITS_SIZE = [
+const UNITS_SIZE = [
   {unit: 'B', name: 'Bytes',  count: 1024},
   {unit: 'K', name: 'KBytes', count: 1024},
   {unit: 'M', name: 'MBytes', count: 1024},
   {unit: 'G', name: 'GBytes', count: -1}
 ];
 
-var UNITS_TIME = [
+const UNITS_TIME = [
   {unit: 's', name: 'seconds', count: 60},
   {unit: 'm', name: 'minutes', count: 60},
   {unit: 'h', name: 'hours',   count: 24},
@@ -24,14 +24,14 @@ var UNITS_TIME = [
 ];
 
 function getUnit(units, v) {
-  for (var i = 0; i < units.length; ++i) {
+  for (let i = 0; i < units.length; ++i) {
     if (units[i].count <= 0 || v < units[i].count)
       return [v, units[i]];
     v /= units[i].count;
   }
 }
 
-var LANGS = [
+const LANGS = [
   {lang: 'bash',       ext: '.sh',         style: '#'},
   {lang: 'c',          ext: '.c',          style: 'c'},
   {lang: 'cpp',        ext: '.cpp',        style: 'c'},
@@ -48,7 +48,7 @@ var LANGS = [
   {lang: 'swift',      ext: '.swift',      style: 'c'}
 ];
 
-var h = {};
+const h = {};
 
 h.KEYS = {
   user:     '../user',
@@ -70,8 +70,8 @@ h.prettyState = function(state) {
 };
 
 h.prettyText = function(text, yesNo) {
-  var chalk = require('./chalk');
-  var icon = require('./icon');
+  const chalk = require('./chalk');
+  const icon = require('./icon');
   switch (yesNo) {
     case true:  return chalk.green(icon.yes + text);
     case false: return chalk.red(icon.no + text);
@@ -80,17 +80,17 @@ h.prettyText = function(text, yesNo) {
 };
 
 h.prettySize = function(n) {
-  var res = getUnit(UNITS_SIZE, n);
+  const res = getUnit(UNITS_SIZE, n);
   return res[0].toFixed(2) + res[1].unit;
 };
 
 h.prettyTime = function(n) {
-  var res = getUnit(UNITS_TIME, n);
+  const res = getUnit(UNITS_TIME, n);
   return res[0].toFixed(0) + ' ' + res[1].name;
 };
 
 h.prettyLevel = function(level) {
-  var chalk = require('./chalk');
+  const chalk = require('./chalk');
   switch (level.toLowerCase().trim()) {
     case 'easy':   return chalk.green(level);
     case 'medium': return chalk.yellow(level);
@@ -124,23 +124,23 @@ h.statusToName = function(sc) {
 };
 
 h.langToExt = function(lang) {
-  var res = LANGS.find(function(x) { return x.lang === lang; });
+  const res = LANGS.find(function(x) { return x.lang === lang; });
   return res ? res.ext : '.raw';
 };
 
 h.extToLang = function(fullpath) {
   // HACK: compatible with old ext
   if (fullpath.endsWith('.py3')) return 'python3';
 
-  var res = _.chain(LANGS)
+  const res = _.chain(LANGS)
     .filter(function(x) { return fullpath.endsWith(x.ext); })
     .sortBy(function(x) { return -x.ext.length; })
     .value();
   return res.length ? res[0].lang : 'unknown';
 };
 
 h.langToCommentStyle = function(lang) {
-  var res = LANGS.find(function(x) { return x.lang === lang; });
+  const res = LANGS.find(function(x) { return x.lang === lang; });
 
   return (res && res.style === '#') ?
   {start: '#',  line: '#',  end: '#'} :
@@ -155,11 +155,11 @@ h.mkdir = function(fullpath) {
 h.getCodeDirData = function(dir) {
   dir = h.getCodeDir(dir);
   return fs.readdirSync(dir).map(function(file) {
-    var fullpath = path.join(dir, file);
-    var ext = path.extname(file);
+    const fullpath = path.join(dir, file);
+    const ext = path.extname(file);
 
-    var name = path.basename(file, ext);
-    var data = null;
+    const name = path.basename(file, ext);
+    let data = null;
 
     switch (ext) {
       case '.js':   data = require(fullpath); break;
@@ -206,14 +206,14 @@ h.getPluginFile = function(name) {
 };
 
 h.readStdin = function(cb) {
-  var stdin = process.stdin;
-  var bufs = [];
+  const stdin = process.stdin;
+  const bufs = [];
 
   console.log('NOTE: to finish the input, press ' +
       (this.isWindows() ? '<Ctrl-D> and <Return>' : '<Ctrl-D>'));
 
   stdin.on('readable', function() {
-    var data = stdin.read();
+    const data = stdin.read();
     if (data) {
       // windows doesn't treat ctrl-D as EOF
       if (h.isWindows() && data.toString() === '\x04\r\n') {
@@ -230,13 +230,13 @@ h.readStdin = function(cb) {
 };
 
 h.getSetCookieValue = function(resp, key) {
-  var cookies = resp.headers['set-cookie'];
+  const cookies = resp.headers['set-cookie'];
   if (!cookies) return null;
 
-  for (var i = 0; i < cookies.length; ++i) {
-    var sections = cookies[i].split(';');
-    for (var j = 0; j < sections.length; ++j) {
-      var kv = sections[j].trim().split('=');
+  for (let i = 0; i < cookies.length; ++i) {
+    const sections = cookies[i].split(';');
+    for (let j = 0; j < sections.length; ++j) {
+      const kv = sections[j].trim().split('=');
       if (kv[0] === key) return kv[1];
     }
   }
@@ -253,7 +253,7 @@ h.spin = function(s) {
   return ora(require('./chalk').gray(s)).start();
 };
 
-var COLORS = {
+const COLORS = {
   blue:    {fg: 'white', bg: 'bgBlue'},
   gray:    {fg: 'white', bg: 'bgGray'},
   green:   {fg: 'black', bg: 'bgGreen'},
@@ -265,9 +265,9 @@ h.badge = function(s, color) {
   s = ' ' + s + ' ';
   if (color === 'random')
     color = _.chain(COLORS).keys().sample().value();
-  var c = COLORS[color || 'blue'];
+  const c = COLORS[color || 'blue'];
 
-  var chalk = require('./chalk');
+  const chalk = require('./chalk');
   return chalk[c.fg][c.bg](s);
 };
 

lib/icon.js

@@ -3,7 +3,7 @@ var _ = require('underscore');
 
 var h = require('./helper');
 
-var icons = {
+const icons = {
   yes:    '✔',
   no:     '✘',
   like:   '★',
@@ -15,8 +15,8 @@ var icons = {
 };
 
 icons.setTheme = function(name) {
-  var defaultName = h.isWindows() ? 'win7' : 'default';
-  var theme = this.themes[name] || this.themes[defaultName] || {};
+  const defaultName = h.isWindows() ? 'win7' : 'default';
+  const theme = this.themes[name] || this.themes[defaultName] || {};
   _.extendOwn(this, theme);
 };
 

lib/log.js

@@ -4,7 +4,7 @@ var sprintf = require('sprintf-js').sprintf;
 
 var chalk = require('./chalk');
 
-var log = {
+const log = {
   output: _.bind(console.log, console),
   level:  null,
   levels: {
@@ -37,15 +37,13 @@ log.init = function() {
 
   _.keys(this.levels).forEach(function(name) {
     log[name.toLowerCase()] = function() {
-      var level = log.levels[name];
+      const level = log.levels[name];
       if (log.level.value > level.value) return;
 
-      var args = _.toArray(arguments);
+      const args = _.toArray(arguments);
       if (name !== 'INFO') args.unshift('[' + name + ']');
 
-      var s = args.map(function(arg) {
-        return arg.toString();
-      }).join(' ');
+      let s = args.map(function(arg) { return arg.toString(); }).join(' ');
       if (level.color) s = chalk[level.color](s);
 
       this.output(s);

lib/plugin.js

@@ -37,9 +37,9 @@ Plugin.prototype.setNext = function(next) {
 Plugin.prototype.install = function(cb) {
   if (this.deps.length === 0) return cb();
 
-  var cmd = 'npm install --save ' + this.deps.join(' ');
+  const cmd = 'npm install --save ' + this.deps.join(' ');
   log.debug(cmd);
-  var spin = h.spin(cmd);
+  const spin = h.spin(cmd);
   cp.exec(cmd, {cwd: h.getCodeDir()}, function() {
     spin.stop();
     return cb();
@@ -51,9 +51,9 @@ Plugin.prototype.help = function() {};
 Plugin.plugins = [];
 
 Plugin.init = function(head) {
-  var plugins = [];
+  let plugins = [];
   h.getCodeDirData('lib/plugins').forEach(function(f) {
-    var p = f.data;
+    const p = f.data;
     if (!p) return;
 
     p.file = f.file;
@@ -76,7 +76,7 @@ Plugin.init = function(head) {
     return -p.id;
   });
 
-  var last = head;
+  let last = head;
   plugins.forEach(function(p) {
     if (!p.enabled) return;
     last.setNext(p);
@@ -90,9 +90,9 @@ Plugin.copy = function(src, cb) {
   if (path.extname(src) !== '.js') {
     src = config.sys.urls.plugin.replace('$name', src);
   }
-  var dst = h.getPluginFile(src);
+  const dst = h.getPluginFile(src);
 
-  var srcstream = src.startsWith('https://') ? request(src) : fs.createReadStream(src);
+  const srcstream = src.startsWith('https://') ? request(src) : fs.createReadStream(src);
   srcstream.on('response', function(resp) {
     if (resp.statusCode !== 200)
       srcstream.emit('error', 'HTTP Error: ' + resp.statusCode);
@@ -103,14 +103,14 @@ Plugin.copy = function(src, cb) {
     return cb(e);
   });
 
-  var dststream = fs.createWriteStream(dst);
+  const dststream = fs.createWriteStream(dst);
   dststream.on('close', function() {
     spin.stop();
     return cb(null, dst);
   });
 
   log.debug('copying from ' + src);
-  var spin = h.spin('Downloading ' + src);
+  const spin = h.spin('Downloading ' + src);
   srcstream.pipe(dststream);
 };
 
@@ -119,7 +119,7 @@ Plugin.install = function(name, cb) {
     if (e) return log.error(e);
     log.debug('copied to ' + fullpath);
 
-    var plugin = require(fullpath);
+    const plugin = require(fullpath);
     plugin.install(function() {
       return cb(null, plugin);
     });

lib/plugins/cache.js

@@ -7,15 +7,15 @@ var log = require('../log');
 var Plugin = require('../plugin');
 var session = require('../session');
 
-var plugin = new Plugin(50, 'cache', '', 'Plugin to provide local cache.');
+const plugin = new Plugin(50, 'cache', '', 'Plugin to provide local cache.');
 
 plugin.init = function() {
   Plugin.prototype.init.call(this);
   cache.init();
 };
 
 plugin.getProblems = function(cb) {
-  var problems = cache.get(h.KEYS.problems);
+  const problems = cache.get(h.KEYS.problems);
   if (problems) {
     log.debug('cache hit: problems.json');
     return cb(null, problems);
@@ -30,8 +30,8 @@ plugin.getProblems = function(cb) {
 };
 
 plugin.getProblem = function(problem, cb) {
-  var k = h.KEYS.problem(problem);
-  var _problem = cache.get(k);
+  const k = h.KEYS.problem(problem);
+  const _problem = cache.get(k);
   if (_problem) {
     log.debug('cache hit: ' + k + '.json');
     _.extendOwn(problem, _problem);
@@ -50,15 +50,15 @@ plugin.saveProblem = function(problem) {
   // it would be better to leave specific problem cache being user
   // independent, thus try to reuse existing cache as much as possible
   // after changing user.
-  var _problem = _.omit(problem, ['locked', 'state', 'starred']);
+  const _problem = _.omit(problem, ['locked', 'state', 'starred']);
   return cache.set(h.KEYS.problem(problem), _problem);
 };
 
 plugin.updateProblem = function(problem, kv) {
-  var problems = cache.get(h.KEYS.problems);
+  const problems = cache.get(h.KEYS.problems);
   if (!problems) return false;
 
-  var _problem = problems.find(function(x) { return x.id === problem.id; });
+  const _problem = problems.find(function(x) { return x.id === problem.id; });
   if (!_problem) return false;
 
   _.extend(_problem, kv);

lib/plugins/leetcode.js

@@ -13,7 +13,7 @@ var Plugin = require('../plugin');
 var Queue = require('../queue');
 var session = require('../session');
 
-var plugin = new Plugin(10, 'leetcode', '',
+const plugin = new Plugin(10, 'leetcode', '',
     'Plugin to talk with leetcode APIs.');
 
 var spin;
@@ -27,7 +27,7 @@ function signOpts(opts, user) {
 }
 
 function makeOpts(url) {
-  var opts = {};
+  const opts = {};
   opts.url = url;
   opts.headers = {};
 
@@ -38,7 +38,7 @@ function makeOpts(url) {
 
 function checkError(e, resp, expectedStatus) {
   if (!e && resp && resp.statusCode !== expectedStatus) {
-    var code = resp.statusCode;
+    const code = resp.statusCode;
     log.debug('http error: ' + code);
 
     if (code === 403 || code === 401) {
@@ -52,8 +52,8 @@ function checkError(e, resp, expectedStatus) {
 
 plugin.getProblems = function(cb) {
   log.debug('running leetcode.getProblems');
-  var problems = [];
-  var getCategory = function(category, queue, cb) {
+  let problems = [];
+  const getCategory = function(category, queue, cb) {
     plugin.getCategoryProblems(category, function(e, _problems) {
       if (e) {
         log.debug(category + ': failed to getProblems: ' + e.msg);
@@ -66,7 +66,7 @@ plugin.getProblems = function(cb) {
   };
 
   spin = h.spin('Downloading problems');
-  var q = new Queue(config.sys.categories, {}, getCategory);
+  const q = new Queue(config.sys.categories, {}, getCategory);
   q.run(null, function(e) {
     spin.stop();
     return cb(e, problems);
@@ -75,14 +75,14 @@ plugin.getProblems = function(cb) {
 
 plugin.getCategoryProblems = function(category, cb) {
   log.debug('running leetcode.getCategoryProblems: ' + category);
-  var opts = makeOpts(config.sys.urls.problems.replace('$category', category));
+  const opts = makeOpts(config.sys.urls.problems.replace('$category', category));
 
   spin.text = 'Downloading category ' + category;
   request(opts, function(e, resp, body) {
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
-    var json = JSON.parse(body);
+    const json = JSON.parse(body);
 
     // leetcode permits anonymous access to the problem list
     // while we require login first to make a better experience.
@@ -91,11 +91,11 @@ plugin.getCategoryProblems = function(category, cb) {
       return cb(session.errors.EXPIRED);
     }
 
-    var user = session.getUser();
+    const user = session.getUser();
     user.paid = json.is_paid;
     session.saveUser(user);
 
-    var problems = json.stat_status_pairs
+    const problems = json.stat_status_pairs
         .filter(function(p) {
           return !p.stat.question__hide;
         })
@@ -120,10 +120,10 @@ plugin.getCategoryProblems = function(category, cb) {
 
 plugin.getProblem = function(problem, cb) {
   log.debug('running leetcode.getProblem');
-  var user = session.getUser();
+  const user = session.getUser();
   if (problem.locked && !user.paid) return cb('failed to load locked problem!');
 
-  var opts = makeOpts(config.sys.urls.problem_detail);
+  const opts = makeOpts(config.sys.urls.problem_detail);
   opts.headers.Origin = config.sys.urls.base;
   opts.headers.Referer = problem.link;
 
@@ -146,13 +146,13 @@ plugin.getProblem = function(problem, cb) {
     operationName: 'getQuestionDetail'
   };
 
-  var spin = h.spin('Downloading ' + problem.slug);
+  const spin = h.spin('Downloading ' + problem.slug);
   request.post(opts, function(e, resp, body) {
     spin.stop();
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
-    var q = body.data.question;
+    const q = body.data.question;
     if (!q) return cb('failed to load problem!');
 
     problem.totalAC = JSON.parse(q.stats).totalAccepted;
@@ -183,7 +183,7 @@ function runCode(opts, problem, cb) {
     typed_code:  h.getFileData(problem.file)
   });
 
-  var spin = h.spin('Sending code to judge');
+  const spin = h.spin('Sending code to judge');
   request(opts, function(e, resp, body) {
     spin.stop();
     e = checkError(e, resp, 200);
@@ -200,7 +200,7 @@ function runCode(opts, problem, cb) {
       ++opts._delay;
       log.debug('Will retry after %d seconds...', opts._delay);
 
-      var reRun = _.partial(runCode, opts, problem, cb);
+      const reRun = _.partial(runCode, opts, problem, cb);
       return setTimeout(reRun, opts._delay * 1000);
     }
 
@@ -212,17 +212,17 @@ function runCode(opts, problem, cb) {
 }
 
 function verifyResult(task, queue, cb) {
-  var opts = queue.ctx.opts;
+  const opts = queue.ctx.opts;
   opts.method = 'GET';
   opts.url = config.sys.urls.verify.replace('$id', task.id);
 
-  var spin = h.spin('Waiting for judge result');
+  const spin = h.spin('Waiting for judge result');
   request(opts, function(e, resp, body) {
     spin.stop();
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
-    var result = JSON.parse(body);
+    let result = JSON.parse(body);
     if (result.state === 'SUCCESS') {
       result = formatResult(result);
       _.extendOwn(result, task);
@@ -235,7 +235,7 @@ function verifyResult(task, queue, cb) {
 }
 
 function formatResult(result) {
-  var x = {
+  const x = {
     ok:       result.run_success,
     answer:   result.code_answer || '',
     runtime:  result.status_runtime || '',
@@ -269,17 +269,17 @@ function formatResult(result) {
 
 plugin.testProblem = function(problem, cb) {
   log.debug('running leetcode.testProblem');
-  var opts = makeOpts(config.sys.urls.test.replace('$slug', problem.slug));
+  const opts = makeOpts(config.sys.urls.test.replace('$slug', problem.slug));
   opts.body = {data_input: problem.testcase};
 
   runCode(opts, problem, function(e, task) {
     if (e) return cb(e);
 
-    var tasks = [
+    const tasks = [
       {type: 'Actual', id: task.interpret_id},
       {type: 'Expected', id: task.interpret_expected_id}
     ];
-    var q = new Queue(tasks, {opts: opts, results: []}, verifyResult);
+    const q = new Queue(tasks, {opts: opts, results: []}, verifyResult);
     q.run(null, function(e, ctx) {
       return cb(e, ctx.results);
     });
@@ -288,14 +288,14 @@ plugin.testProblem = function(problem, cb) {
 
 plugin.submitProblem = function(problem, cb) {
   log.debug('running leetcode.submitProblem');
-  var opts = makeOpts(config.sys.urls.submit.replace('$slug', problem.slug));
+  const opts = makeOpts(config.sys.urls.submit.replace('$slug', problem.slug));
   opts.body = {judge_type: 'large'};
 
   runCode(opts, problem, function(e, task) {
     if (e) return cb(e);
 
-    var tasks = [{type: 'Actual', id: task.submission_id}];
-    var q = new Queue(tasks, {opts: opts, results: []}, verifyResult);
+    const tasks = [{type: 'Actual', id: task.submission_id}];
+    const q = new Queue(tasks, {opts: opts, results: []}, verifyResult);
     q.run(null, function(e, ctx) {
       return cb(e, ctx.results);
     });
@@ -304,15 +304,15 @@ plugin.submitProblem = function(problem, cb) {
 
 plugin.getSubmissions = function(problem, cb) {
   log.debug('running leetcode.getSubmissions');
-  var opts = makeOpts(config.sys.urls.submissions.replace('$slug', problem.slug));
+  const opts = makeOpts(config.sys.urls.submissions.replace('$slug', problem.slug));
   opts.headers.Referer = config.sys.urls.problem.replace('$slug', problem.slug);
 
   request(opts, function(e, resp, body) {
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
     // FIXME: this only return the 1st 20 submissions, we should get next if necessary.
-    var submissions = JSON.parse(body).submissions_dump;
+    const submissions = JSON.parse(body).submissions_dump;
     submissions.forEach(function(submission) {
       submission.id = _.last(_.compact(submission.url.split('/')));
     });
@@ -323,13 +323,13 @@ plugin.getSubmissions = function(problem, cb) {
 
 plugin.getSubmission = function(submission, cb) {
   log.debug('running leetcode.getSubmission');
-  var opts = makeOpts(config.sys.urls.submission.replace('$id', submission.id));
+  const opts = makeOpts(config.sys.urls.submission.replace('$id', submission.id));
 
   request(opts, function(e, resp, body) {
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
-    var re = body.match(/submissionCode:\s('[^']*')/);
+    let re = body.match(/submissionCode:\s('[^']*')/);
     if (re) submission.code = eval(re[1]);
 
     re = body.match(/distribution_formatted:\s('[^']+')/);
@@ -340,11 +340,11 @@ plugin.getSubmission = function(submission, cb) {
 
 plugin.starProblem = function(problem, starred, cb) {
   log.debug('running leetcode.starProblem');
-  var opts = makeOpts();
+  const opts = makeOpts();
   opts.headers.Origin = config.sys.urls.base;
   opts.headers.Referer = problem.link;
 
-  var user = session.getUser();
+  const user = session.getUser();
   if (starred) {
     opts.url = config.sys.urls.favorites;
     opts.method = 'POST';
@@ -370,28 +370,28 @@ plugin.starProblem = function(problem, starred, cb) {
 
 plugin.getFavorites = function(cb) {
   log.debug('running leetcode.getFavorites');
-  var opts = makeOpts(config.sys.urls.favorites);
+  const opts = makeOpts(config.sys.urls.favorites);
 
   request(opts, function(e, resp, body) {
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
-    var favorites = JSON.parse(body);
+    const favorites = JSON.parse(body);
     return cb(null, favorites);
   });
 };
 
 plugin.signin = function(user, cb) {
   log.debug('running leetcode.signin');
-  var spin = h.spin('Signing in leetcode.com');
+  const spin = h.spin('Signing in leetcode.com');
   request(config.sys.urls.login, function(e, resp, body) {
     spin.stop();
     e = checkError(e, resp, 200);
     if (e) return cb(e);
 
     user.loginCSRF = h.getSetCookieValue(resp, 'csrftoken');
 
-    var opts = {
+    const opts = {
       url:     config.sys.urls.login,
       headers: {
         Origin:  config.sys.urls.base,
@@ -420,7 +420,7 @@ plugin.getUser = function(user, cb) {
   plugin.getFavorites(function(e, favorites) {
     if (e) return cb(e);
 
-    var favorite = favorites.favorites.private_favorites.find(function(f) {
+    const favorite = favorites.favorites.private_favorites.find(function(f) {
       return f.name === 'Favorite';
     });
     user.hash = favorite.id_hash;

lib/plugins/retry.js

@@ -9,14 +9,14 @@ var session = require('../session');
 var plugin = new Plugin(30, 'retry', '',
     'Plugin to retry last failed request if autologin.enable is on.');
 
-var count = {};
+const count = {};
 
 function canRetry(e, name) {
   return e && config.autologin.enable && (e === session.errors.EXPIRED) && count[name] < 1;
 }
 
 plugin.init = function() {
-  var names = [
+  const names = [
     'getProblems',
     'getProblem',
     'getSubmissions',
@@ -30,12 +30,12 @@ plugin.init = function() {
   names.forEach(function(name) {
     count[name] = 0;
     plugin[name] = function() {
-      var args = _.toArray(arguments);
-      var cb = args.pop();
+      const args = _.toArray(arguments);
+      const cb = args.pop();
 
-      var _cb = function() {
-        var results = _.toArray(arguments);
-        var e = results[0];
+      const _cb = function() {
+        const results = _.toArray(arguments);
+        const e = results[0];
         if (!canRetry(e, name)) {
           count[name] = 0;
           return cb.apply(null, results);
@@ -48,7 +48,7 @@ plugin.init = function() {
         });
       };
 
-      var next = plugin.next;
+      const next = plugin.next;
       next[name].apply(next, args.concat(_cb));
     };
   });
@@ -61,7 +61,7 @@ plugin.init = function() {
 plugin.relogin = function(cb) {
   log.debug('session expired, try to re-login...');
 
-  var user = session.getUser();
+  const user = session.getUser();
   if (!user) {
     log.debug('relogin failed: no user found, please login again');
     return cb();

lib/queue.js

@@ -24,8 +24,8 @@ Queue.prototype.run = function(concurrency, onDone) {
   this.concurrency = concurrency || config.network.concurrency || 1;
   this.onDone = onDone;
 
-  var self = this;
-  for (var i = 0; i < this.concurrency; ++i) {
+  const self = this;
+  for (let i = 0; i < this.concurrency; ++i) {
     setImmediate(function() { self.workerRun(); });
   }
 };
@@ -38,8 +38,8 @@ Queue.prototype.workerRun = function() {
     return;
   }
 
-  var task = this.tasks.shift();
-  var self = this;
+  const task = this.tasks.shift();
+  const self = this;
   this.onTask(task, self, function(e) {
     if (e) self.error = e;
 

lib/session.js

@@ -6,7 +6,7 @@ var cache = require('./cache');
 var config = require('./config');
 var h = require('./helper');
 
-var session = {};
+const session = {};
 
 session.errors = {
   EXPIRED: {
@@ -22,7 +22,7 @@ session.getUser = function() {
 session.saveUser = function(user) {
   // when auto login enabled, have to save password to re-login later
   // otherwise don't dump password for the sake of security.
-  var _user = _.omit(user, config.autologin.enable ? [] : ['pass']);
+  const _user = _.omit(user, config.autologin.enable ? [] : ['pass']);
   cache.set(h.KEYS.user, _user);
 };
 
@@ -36,9 +36,9 @@ session.isLogin = function() {
 
 session.updateStat = function(k, v) {
   // TODO: use other storage if too many stat data
-  var today = moment().format('YYYY-MM-DD');
-  var stats = cache.get(h.KEYS.stat) || {};
-  var stat = stats[today] = stats[today] || {};
+  const today = moment().format('YYYY-MM-DD');
+  const stats = cache.get(h.KEYS.stat) || {};
+  const stat = stats[today] = stats[today] || {};
   stat[k] = stat[k] || 0;
   stat[k] += v;
   cache.set(h.KEYS.stat, stats);