浅谈JavaScript 代码简洁之道(7)

日期：2020-05-11 栏目：程序人生浏览：次

Good:

function newRequestModule(url) {
 // ...
}

const req = newRequestModule;
inventoryTracker('apples', req, 'www.inventory-awesome.io');

对象和数据结构

用 get、set 方法操作数据

这样做可以带来很多好处，比如在操作数据时打日志，方便跟踪错误；在 set 的时候很容易对数据进行校验…

Bad:

function makeBankAccount() {
 // ...

 return {
 balance: 0,
 // ...
 };
}

const account = makeBankAccount();
account.balance = 100;

Good:

function makeBankAccount() {
 // 私有变量
 let balance = 0;

 function getBalance() {
 return balance;
 }

 function setBalance(amount) {
 // ... 在更新 balance 前，对 amount 进行校验
 balance = amount;
 }

 return {
 // ...
 getBalance,
 setBalance,
 };
}

const account = makeBankAccount();
account.setBalance(100);

使用私有变量

可以用闭包来创建私有变量

Bad:

const Employee = function(name) {
 this.name = name;
};

Employee.prototype.getName = function getName() {
 return this.name;
};

const employee = new Employee('John Doe');
console.log(`Employee name: ${employee.getName()}`); 
// Employee name: John Doe
delete employee.name;
console.log(`Employee name: ${employee.getName()}`);
 // Employee name: undefined

Good:

function makeEmployee(name) {
 return {
 getName() {
  return name;
 },
 };
}

const employee = makeEmployee('John Doe');
console.log(`Employee name: ${employee.getName()}`); 
// Employee name: John Doe
delete employee.name;
console.log(`Employee name: ${employee.getName()}`); 
// Employee name: John Doe

类

使用 class

在 ES2015/ES6 之前，没有类的语法，只能用构造函数的方式模拟类，可读性非常差。

Bad:

// 动物
const Animal = function(age) {
 if (!(this instanceof Animal)) {
 throw new Error('Instantiate Animal with `new`');
 }

 this.age = age;
};

Animal.prototype.move = function move() {};

// 哺乳动物
const Mammal = function(age, furColor) {
 if (!(this instanceof Mammal)) {
 throw new Error('Instantiate Mammal with `new`');
 }

 Animal.call(this, age);
 this.furColor = furColor;
};

Mammal.prototype = Object.create(Animal.prototype);
Mammal.prototype.constructor = Mammal;
Mammal.prototype.liveBirth = function liveBirth() {};

// 人类
const Human = function(age, furColor, languageSpoken) {
 if (!(this instanceof Human)) {
 throw new Error('Instantiate Human with `new`');
 }

 Mammal.call(this, age, furColor);
 this.languageSpoken = languageSpoken;
};

Human.prototype = Object.create(Mammal.prototype);
Human.prototype.constructor = Human;
Human.prototype.speak = function speak() {};

转载注明出处：http://www.heiqu.com/90.html

浅谈JavaScript 代码简洁之道(7)

对象和数据结构

类

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