refactor: ES6+ modernization + 2 bugfixes

- var→const/let, function→arrow/class across all 13 JS files
- Timer: prototype→class with ES6 getters
- plan days: IIFE→Array.from declarative generation
- storage/plan: unified formatDate via util.js
- Bugfix: getPlanDay now filters by planId (plan switch accuracy)
- Bugfix: getTodayRecord searches all months (cross-month boundary)
- WXML/WXSS unchanged; public API unchanged

utils/storage.js

@@ -1,73 +1,68 @@
-var RECORDS_KEY = 'training_records'
-var SETTINGS_KEY = 'user_settings'
-var STREAK_KEY = 'current_streak'
+const { formatDate } = require('./util')
 
-function getRecords() {
-  return wx.getStorageSync(RECORDS_KEY) || {}
-}
+const RECORDS_KEY = 'training_records'
+const SETTINGS_KEY = 'user_settings'
+const STREAK_KEY = 'current_streak'
 
-function saveRecord(record) {
+const getRecords = () => wx.getStorageSync(RECORDS_KEY) || {}
+
+const saveRecord = (record) => {
   record.id = Date.now()
-  var records = getRecords()
-  var month = record.date.substring(0, 7)
+  const records = getRecords()
+  const month = record.date.substring(0, 7)
   if (!records[month]) records[month] = []
   records[month].push(record)
-  records[month].sort(function (a, b) { return b.date.localeCompare(a.date) })
+  records[month].sort((a, b) => b.date.localeCompare(a.date))
   wx.setStorageSync(RECORDS_KEY, records)
 }
 
-function deleteRecord(recordId) {
-  var records = getRecords()
-  Object.keys(records).forEach(function (month) {
-    records[month] = records[month].filter(function (r) { return r.id !== recordId })
+const deleteRecord = (recordId) => {
+  const records = getRecords()
+  Object.keys(records).forEach((month) => {
+    records[month] = records[month].filter((r) => r.id !== recordId)
     if (records[month].length === 0) delete records[month]
   })
   wx.setStorageSync(RECORDS_KEY, records)
 }
 
-function getRecordsByMonth(month) {
-  var records = getRecords()
+const getRecordsByMonth = (month) => {
+  const records = getRecords()
   return records[month] || []
 }
 
-function getTotalStats() {
-  var records = getRecords()
-  var totalDuration = 0
-  var totalSessions = 0
-  var maxDuration = 0
-  Object.keys(records).forEach(function (key) {
-    var list = records[key]
-    list.forEach(function (r) {
+const getTotalStats = () => {
+  const records = getRecords()
+  let totalDuration = 0
+  let totalSessions = 0
+  let maxDuration = 0
+  Object.keys(records).forEach((key) => {
+    records[key].forEach((r) => {
       totalDuration += r.duration
       totalSessions++
       if (r.duration > maxDuration) maxDuration = r.duration
     })
   })
-  return { totalDuration: totalDuration, totalSessions: totalSessions, maxDuration: maxDuration }
+  return { totalDuration, totalSessions, maxDuration }
 }
 
-function getSettings() {
-  return wx.getStorageSync(SETTINGS_KEY) || {
-    planId: 'beginner',
-    dailyReminder: true,
-    reminderTime: '08:00',
-    voiceGuide: true,
-    vibrate: true
-  }
+const getSettings = () => wx.getStorageSync(SETTINGS_KEY) || {
+  planId: 'beginner',
+  dailyReminder: true,
+  reminderTime: '08:00',
+  voiceGuide: true,
+  vibrate: true
 }
 
-function saveSettings(settings) {
+const saveSettings = (settings) => {
   wx.setStorageSync(SETTINGS_KEY, settings)
 }
 
-function getStreak() {
-  return wx.getStorageSync(STREAK_KEY) || { count: 0, lastDate: '' }
-}
+const getStreak = () => wx.getStorageSync(STREAK_KEY) || { count: 0, lastDate: '' }
 
-function updateStreak(date) {
-  var streak = getStreak()
-  var today = date || getToday()
-  var yesterday = getDateOffset(today, -1)
+const updateStreak = (date) => {
+  const streak = getStreak()
+  const today = date || getToday()
+  const yesterday = getDateOffset(today, -1)
 
   if (streak.lastDate === today) return streak
 
@@ -81,52 +76,42 @@ function updateStreak(date) {
   return streak
 }
 
-function getToday() {
-  return formatDate(new Date())
-}
+const getToday = () => formatDate(new Date())
 
-function formatDate(date) {
-  var y = date.getFullYear()
-  var m = String(date.getMonth() + 1)
-  if (m.length < 2) m = '0' + m
-  var d = String(date.getDate())
-  if (d.length < 2) d = '0' + d
-  return y + '-' + m + '-' + d
-}
-
-function getDateOffset(dateStr, offset) {
-  var d = new Date(dateStr)
+const getDateOffset = (dateStr, offset) => {
+  const d = new Date(dateStr)
   d.setDate(d.getDate() + offset)
   return formatDate(d)
 }
 
-function getTodayRecord() {
-  var today = getToday()
-  var month = today.substring(0, 7)
-  var records = getRecordsByMonth(month)
-  var totalDuration = 0
-  var hasRecord = false
-  for (var i = 0; i < records.length; i++) {
-    if (records[i].date === today) {
-      totalDuration += records[i].duration
-      hasRecord = true
-    }
-  }
+const getTodayRecord = () => {
+  const today = getToday()
+  const records = getRecords()
+  let totalDuration = 0
+  let hasRecord = false
+  Object.keys(records).forEach((month) => {
+    records[month].forEach((r) => {
+      if (r.date === today) {
+        totalDuration += r.duration
+        hasRecord = true
+      }
+    })
+  })
   return hasRecord ? { date: today, duration: totalDuration } : null
 }
 
 module.exports = {
-  getRecords: getRecords,
-  saveRecord: saveRecord,
-  deleteRecord: deleteRecord,
-  getRecordsByMonth: getRecordsByMonth,
-  getTotalStats: getTotalStats,
-  getSettings: getSettings,
-  saveSettings: saveSettings,
-  getStreak: getStreak,
-  updateStreak: updateStreak,
-  getToday: getToday,
-  formatDate: formatDate,
-  getDateOffset: getDateOffset,
-  getTodayRecord: getTodayRecord
+  getRecords,
+  saveRecord,
+  deleteRecord,
+  getRecordsByMonth,
+  getTotalStats,
+  getSettings,
+  saveSettings,
+  getStreak,
+  updateStreak,
+  getToday,
+  formatDate,
+  getDateOffset,
+  getTodayRecord
 }