JS 中 if-else 优化写法三元运算适合简单的 if(){}else{} 情况三元运算优化：逻辑与运算符使

三元运算

适合简单的 if(){}else{} 情况

let result = null
if(a>0){
  result = true
} else {
   result = false
}

三元运算优化：

a>0 ? result = true : result = false

逻辑与运算符

使用逻辑与运算符来简化代码

if(flag){
   something()
}

逻辑与运算符优化：

flag && something()

`includes` 处理多重条件

if(code === 200 || code === 300 || code === 202){
  dosomthing()
}

使用includes优化

if([200,300,202].includes(code)){
 dosomthing()
}

一元判断,存到Object里

const actions = {
      '1': ['processing','IndexPage'],
      '2': ['fail','FailPage'],
      '3': ['fail','FailPage'],
      '4': ['success','SuccessPage'],
      '5': ['cancel','CancelPage'],
      'default': ['other','Index'],
    }
    /**
     * 按钮点击事件
     * @param {number} status 活动状态：1开团进行中 2开团失败 3 商品售罄 4 开团成功 5 系统取消
     */
     
     const onButtonClick = (status)=>{
      let action = actions[status] || actions['default'],
          logName = action[0],
          pageName = action[1]
      sendLog(logName)
      jumpTo(pageName)
    }

一元判断,存到Map里

const actions = newMap([[1, ['processing','IndexPage']],
[2, ['fail','FailPage']],
[3, ['fail','FailPage']],
[4, ['success','SuccessPage']],
[5, ['cancel','CancelPage']],
['default', ['other','Index']]
])
/**
* 按钮点击事件\
* @param {number} status 活动状态：1 开团进行中 2 开团失败 3 商品售罄 4 开团成功 5 系统取消\
*/

const onButtonClick = (status)=>{
let action = actions.get(status) || actions.get('default')
sendLog(action[0])
jumpTo(action[1])
}

多元判断时：将condition拼接成字符串存到Map里

把两个条件拼接成字符串，并通过以条件拼接字符串作为键，以处理函数作为值的Map对象进行查找并执行，这种写法在多元条件判断时候尤其好用

const actions = newMap([
['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*/}],
])

/**
* 按钮点击事件
* @param {string} identity 身份标识：guest客态 master主态
* @param {number} status 活动状态：1 开团进行中 2 开团失败 3 开团成功 4 商品售罄 5 有库存未开团
*/

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

将condition存为Object存到Map里

觉得把查询条件拼成字符串有点别扭，那还有一种方案，就是用Map对象，以Object对象作为key：

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

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

优化重复逻辑部分

将处理逻辑函数进行缓存

const actions = ()=>{
const functionA = ()=>{/*do sth*/}
const functionB = ()=>{/*do sth*/}
return newMap([
[{identity:'guest',status:1},functionA],
[{identity:'guest',status:2},functionA],
[{identity:'guest',status:3},functionA],
[{identity:'guest',status:4},functionA],
[{identity:'guest',status:5},functionB],

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

进一步简化重复逻辑，用正则类型作为key

const actions = ()=>{
const functionA = ()=>{/*do sth*/}
const functionB = ()=>{/*do sth*/}
returnnewMap([
[/^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))
}

多元判断时：正则类型作为key，同时执行公共逻辑和单独逻辑

假如需求是，凡是guest情况都要发送functionC，不同status情况也需要单独的逻辑处理，这里就涉及公共逻辑，和单独逻辑

const actions = ()=>{
const functionA = ()=>{/*do sth*/}
const functionB = ()=>{/*do sth*/}
const functionC = ()=>{/*send log*/}
returnnewMap([
[/^guest_[1-4]$/,functionA],
[/^guest_5$/,functionB],
[/^guest_.*$/,functionC],
//...
])
}

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

参考文章：mp.weixin.qq.com/s?__biz=MzI…

JS 中 if-else 优化写法