複雜邏輯判斷時需要寫很多if/else，程式碼可讀性較差，可以用es6新增的Map來簡化程式碼

列舉六種例項，逐步簡化

/**

 * 按鈕點選事件

 * @param {number} status 活動狀態：1 開團進行中 2 開團失敗 3 商品售罄 4 開團成功 5 系統取消

 */

const onButtonClick = (status) => {

  if (status == 1) {

    sendLog('processing') jumpTo('IndexPage')

  } else if (status == 2) {

    sendLog('fail') jumpTo('FailPage')

  } else if (status == 3) {

    sendLog('fail') jumpTo('FailPage')

  } else if (status == 4) {

    sendLog('success') jumpTo('SuccessPage')

  } else if (status == 5) {

    sendLog('cancel') jumpTo('CancelPage')

  } else {

    sendLog('other') jumpTo('Index')

  }

}
 

轉化成switch簡化：

/**
 * 按鈕點選事件
 * @param {number} status 活動狀態：1 開團進行中 2 開團失敗 3 商品售罄 4 開團成功 5 系統取消
 */
const onButtonClick = (status) => {
  switch (status) {
    case 1:
      sendLog('processing')
      jumpTo('IndexPage')
      break
    case 2:
    case 3:
      sendLog('fail')
      jumpTo('FailPage')
      break
    case 4:
      sendLog('success')
      jumpTo('SuccessPage')
      break
    case 5:
      sendLog('cancel')
      jumpTo('CancelPage')
      break
    default:
      sendLog('other')
      jumpTo('Index')
      break
  }

}
 

將判斷條件作為物件的屬性名，將處理邏輯作為物件的屬性值，繼續簡化：

const actions = {
  '1': ['processing', 'IndexPage'],
  '2': ['fail', 'FailPage'],
  '3': ['fail', 'FailPage'],
  '4': ['success', 'SuccessPage'],
  '5': ['cancel', 'CancelPage'],
  'default': ['other', 'Index'],
}

/**
 * 按鈕點選事件
 * @param {number} status 活動狀態：1開團進行中 2開團失敗 3 商品售罄 4 開團成功 5 系統取消
 */
const onButtonClick = (status) => {
  let action = actions[status] || actions['default'],
    logName = action[0],
    pageName = action[1]
  sendLog(logName)
  jumpTo(pageName)
}
 

轉化成Map簡化

const actions = new Map([
  [1, ['processing', 'IndexPage']],
  [2, ['fail', 'FailPage']],
  [3, ['fail', 'FailPage']],
  [4, ['success', 'SuccessPage']],
  [5, ['cancel', 'CancelPage']],
  ['default', ['other', 'Index']]
])

/**
 * 按鈕點選事件
 * @param {number} status 活動狀態：1 開團進行中 2 開團失敗 3 商品售罄 4 開團成功 5 系統取消
 */
const onButtonClick = (status) => {
  let action = actions.get(status) || actions.get('default')
  sendLog(action[0])
  jumpTo(action[1])
}

Map物件和Object物件的區別：Map的鍵可以是任意值，Map的鍵值對個數可通過size屬性直接獲

接下來將問題升級：

除去判斷狀態還要判斷使用者身份：

傳統寫法：

const actions = new Map([
  ['guest_1', () => { /*do sth*/ }],
  ['guest_2', () => { /*do sth*/ }],
  ['guest_3', () => { /*do sth*/ }],
  ['guest_4', () => { /*do sth*/ }],
  ['guest_5', () => { /*do sth*/ }],
  ['master_1', () => { /*do sth*/ }],
  ['master_2', () => { /*do sth*/ }],
  ['master_3', () => { /*do sth*/ }],
  ['master_4', () => { /*do sth*/ }],
  ['master_5', () => { /*do sth*/ }],
  ['default', () => { /*do sth*/ }],
])
/**
 * 按鈕點選事件
 * @param {string} identity 身份標識：guest客態 master主態
 * @param {number} status 活動狀態：1 開團進行中 2 開團失敗 3 開團成功 4 商品售罄 5 有庫存未開團
 */

const onButtonClick = (identity, status) => {
  let action = actions.get(`${identity}_${status}`) || actions.get('default')
  action.call(this)
}

用物件做鍵值簡化：

const actions = new Map([
  [{
    identity: 'guest',
    status: 1
  }, () => { /*do sth*/ }],
  [{
    identity: 'guest',
    status: 2
  }, () => { /*do sth*/ }],
  //...
])

const onButtonClick = (identity, status) => {
  //下面程式碼使用了陣列解構  [key,value] = cuurrentValue
  let action = [...actions].filter(([key, value]) => (key.identity == identity && key.status == status))
  action.forEach(([key, value]) => value.call(this))
}

正則作為key

const actions = () => {
  const functionA = () => { /*do sth*/ }
  const functionB = () => { /*do sth*/ }
  return new Map([
   [/^guest_[1-4]$/, functionA],
    [/^guest_5$/, functionB],
    //...
  ])
}

const onButtonClick = (identity, status) => {
 let action = [...actions()].filter(([key, value]) => (key.test(`${identity}_${status}`)))
  action.forEach(([key, value]) => value.call(this))
}

參考：https://mp.weixin.qq.com/s/0eX4FgJXMgCmZaKkZb9HVA