5种使JavaScript代码库更干净的方法

web前端开发

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· 2021-05-16

英文 | https://betterprogramming.pub/5-practices-to-make-your-javascript-code-base-cleaner-611300dfe088

翻译 | 杨小二

JavaScript无处不在，从PC端到移动设备端，甚至是后端，都在使用JavaScript。

在本文中，我将尝试一些可用来使代码看起来更简洁的实践方案。

1、使用默认参数代替短路或条件

默认参数通常比短路更干净。

function SomeMethod(paramThatCanBeUndefined) {
   const localValue = paramThatCanBeUndefined || "Default Value";   console.log(localValue)   // ...}SomeMethod() // Default ValueSomeMethod("SomeValue") // SomeValue

尝试以下方法：

function SomeMethod(  console.log(paramThatCanBeUndefined)  // ...}SomeMethod() // Default ValueSomeMethod("SomeValue") // SomeValue

声明：Falsy值，如''，""，false，null，0，和NaN将不会被默认值替代：

function SomeMethod(paramThatCanBeUndefined = "Default Value") {          console.log(paramThatCanBeUndefined)    // ...}SomeMethod(null) // will not Default Value, will null InsteadSomeMethod("SomeValue") // SomeValue

2、处理多个条件

const conditions = ["Condition 2","Condition String2"];someFunction(str){  if(str.includes("someValue1") || str.includes("someValue2")){    return true  }else{    return false  }}

一种更干净的方法是：

someFunction(str){   const conditions = ["someValue1","someValue2"];   return conditions.some(condition=>str.includes(condition));}

3、用动态键值对替换开关（即对象文字）

开关版本（或将开关替换为if / else）：

const UserRole = {  ADMIN: "Admin",  GENERAL_USER: "GeneralUser",  SUPER_ADMIN: "SuperAdmin",};function getRoute(userRole = "default role"){

  switch(userRole){    case UserRole.ADMIN:      return "/admin"    case UserRole.GENERAL_USER:        return "/GENERAL_USER"    case UserRole.SUPER_ADMIN:        return "/superadmin"    default:      return "/"   }
}console.log(getRoute(UserRole.ADMIN)) // return "/admin"console.log(getRoute("Anything")) // return Default pathconsole.log(getRoute()) // return Default pathconsole.log(getRoute(null)) // return Default path
// More cases if new arrive// You can think if else instead of switch

动态键值对版本：

const UserRole = {   ADMIN: "Admin",   GENERAL_USER: "GeneralUser",   SUPER_ADMIN: "SuperAdmin",};function getRoute(userRole = "default role"){ const appRoute = {  [UserRole.ADMIN]: "/admin",  [UserRole.GENERAL_USER]: "/user",  [UserRole.SUPER_ADMIN]: "/superadmin" }; return appRoute[userRole] || "Default path";}console.log(getRoute(UserRole.ADMIN)) // return "/admin"console.log(getRoute("Anything")) // return Default pathconsole.log(getRoute()) // return Default pathconsole.log(getRoute(null)) // return Default path// No more switch/if-else here.// Easy to Further expansion

4、避免过多的函数参数

function myFunction(employeeName,jobTitle,yrExp,majorExp){ return `${employeeName} is working as ${jobTitle} with ${yrExp}    years of experience in ${majorExp}`}//output be like John is working as Project Manager with 12 year of experience in Project Management// you can call it viaconsole.log(myFunction("John","Project Manager",12,"Project Management"))//    ***** PROBLEMS ARE *****// Violation of 'clean code' principle// Parameter sequencing is important// Unused Params warning if not used// Testing need to consider a lot of edge cases.

这是一种更清洁的方法：

function myFunction({employeeName,jobTitle,yrExp,majorExp}){ return `${employeeName} is working as ${jobTitle} with ${yrExp} years of experience in ${majorExp}`}//output be like John is working as Project Manager with 12 year of experience in Project Management// you can call it viaconst mockTechPeople = {  employeeName:"John",  jobTitle:"Project Manager",  yrExp:12,  majorExp:"Project Management"}console.log(myFunction(mockTechPeople))// ES2015/ES6 destructuring syntax is in action// map your desired value to variable you need.

5、使用Object.assign设置默认对象

这看起来很繁琐：

const someObject = { title: null, subTitle: "Subtitle", buttonColor: null, disabled: true};function createOption(someObject) { someObject.title = someObject.title || "Default Title"; someObject.subTitle = someObject.subTitle || "Default Subtitle"; someObject.buttonColor = someObject.buttonColor || "blue"; someObject.disabled = someObject.disabled !== undefined ?  someObject.disabled : true; return someObject}console.log(createOption(someObject));
// Output be like // {title: 'Default Title', subTitle: 'Subtitle', buttonColor: 'blue', disabled: true}

这种方法看起来更好：

const someObject = {  title: null,  subTitle: "Subtitle",  buttonColor: null,  disabled: true }; function creteOption(someObject) {  const newObject = Object.assign({   title: "Default Title",   subTitle: "Default Subtitle",   buttonColor: "blue",   disabled: true },someObject) return newObject } console.log(creteOption(someObject));