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什么是整洁的代码呢?答案可能因人而异,个人提倡以函数式风格编写代码,如果做得正确的话,代码将更容易阅读、分解和测试。在开始函数式编程之前,学习一些小的技巧有助于编写整洁的代码。最好的方式是阅读开源项目,学习别人的方式。对于JavaScript,ES6 引入了许多新的特性,也使得写代码多一种更加优雅的方式。
阅读代码,可以站在巨人的肩膀上快速成长的有效方法,GitHub 是程序员学习的首选资源站。
1. 数组合并
// 常规逻辑
const apples = ["🍎", "🍏"];
const fruits = ["🍉", "🍊", "🍇"].concat(apples);
console.log(fruits); // ["🍉", "🍊", "🍇", "🍎", "🍏"];
// 优雅写法 1
const apples = ["🍎", "🍏"];
const fruits = ["🍉", "🍊", "🍇", ...apples];
console.log(fruits); // ["🍉", "🍊", "🍇", "🍎", "🍏"];
// 优雅写法 2
const apples = ["🍎", "🍏"];
const fruits = [...apples, "🥭", "🍌", "🍒"];
console.log(fruits); // ["🍎", "🍏", "🥭", "🍌", "🍒"];
// 优雅去重
const apples = ["🍎", "🍏", "🍏"];
const fruits = [...new Set(["🍉", "🍊", "🍇", "🍇", ...apples])];
console.log(fruits); // [ '🍉', '🍊', '🍇', '🍎', '🍏' ]
2. 数组中取值
// 常规逻辑
const apples = ["🍎", "🍏"];
const redApple = apples[0];
const greenApple = apples[1];
console.log(redApple); // 🍎
console.log(greenApple); // 🍏;
// 优雅写法
const apples = ["🍎", "🍏"];
const [redApple, greenApple] = apples; // 使用解构赋值
console.log(redApple); // 🍎
console.log(greenApple); // 🍏;
3. 对象取值
// 常规逻辑
const user = {
name: "DevPoint",
age: 30,
};
const name = user.name; // DevPoint
const age = user.age; // 30
console.log(name);
console.log(age);
// 优雅写法
const user = {
name: "DevPoint",
age: 30,
};
const { name, age } = user;
console.log(name); // DevPoint
console.log(age); // 30
4. 数组循环
数组循环的方法有 .forEach()
与 for...of
,在使用上各有特色,但在效率上,for...of
比 .forEach()
快。因此推荐使用 for...of
。
// 常规逻辑
const fruits = ["🍉", "🍊", "🍇", "🍎"];
for (let i = 0; i < fruits.length; i++) {
console.log(fruits[i]);
}
// 优雅写法
const fruits = ["🍉", "🍊", "🍇", "🍎"];
for (fruit of fruits) {
console.log(fruit);
}
5. 箭头函数作为回调
箭头函数是 ES6 中引入新的语法,除了让代码变得优雅的同时,可以避免 this
带来的问题。
// 常规逻辑
const fruits = ["🍉", "🍊", "🍇", "🍎"];
fruits.forEach(function (fruit) {
console.log(fruit);
});
// 优雅写法
const fruits = ["🍉", "🍊", "🍇", "🍎"];
fruits.forEach((fruit) => console.log(fruit));
6. 数组搜索
数组操作,在前端开发中是比较常见的功能,为了提高开发效率降低重复代码,可以考虑写一个通用的数组操作的脚本库。
假设需要通过一个对象的属性从一个对象数组中查找一个对象,通常使用 for 循环:
// 常规逻辑
const inventory = [
{ name: "Bananas", quantity: 5 },
{ name: "Apples", quantity: 10 },
{ name: "Grapes", quantity: 2 },
];
// Get the object with the name `Apples` inside the array
function getApples(arr, value) {
for (let index = 0; index < arr.length; index++) {
if (arr[index].name === "Apples") {
return arr[index];
}
}
}
const result = getApples(inventory);
console.log(result); // { name: 'Apples', quantity: 10 }
// 优雅写法
const inventory = [
{ name: "Bananas", quantity: 5 },
{ name: "Apples", quantity: 10 },
{ name: "Grapes", quantity: 2 },
];
function getApples(arr, value) {
return arr.find((obj) => obj.name === "Apples");
}
const result = getApples(inventory);
console.log(result);
7.字符串转换为数字
// 常规逻辑
const num = parseInt("10");
console.log(num); // 10
console.log(typeof num); // "number";
// 优雅写法
const num = +"10";
console.log(num); //=> 10
console.log(typeof num); // "number"
console.log(+"10" === 10); // true;
同样的方法可以用于判断是否为整数:
const isInteger = (val) => Number.isInteger(+val);
console.log(isInteger("DevPoint")); // false
console.log(isInteger("30")); // true
console.log(isInteger(30)); // true
8. null 值初始化
// 常规逻辑
function getUserRole(role) {
let userRole;
if (role) {
userRole = role;
} else {
userRole = "USER";
}
return userRole;
}
console.log(getUserRole()); // "USER"
console.log(getUserRole("ADMIN")); // "ADMIN";
// 优雅写法
function getUserRole(role) {
return role || "USER"; // 默认值定义的常见方法
}
console.log(getUserRole()); // "USER"
console.log(getUserRole("ADMIN")); // "ADMIN";
9. 字符串拼接
过去无尽的 +
号,再加上一些排版就更痛苦。
// 常规逻辑
const name = "DevPoint";
const message = "Hi " + name + "!";
console.log(message); // Hi DevPoint!
// 优雅写法
const name = "DevPoint";
const message = `Hi ${name}!`;
console.log(message); // Hi DevPoint!
10 对象合并
对象的合并,在ES6中,可以学习一些扩展运算符和解构赋值,这样有利于写出更加简洁的代码。
// 常规逻辑
const employee = { name: "DevPoint", age: 30 };
const salary = { grade: "A" };
const summary = salary;
for (const key in employee) {
summary[key] = employee[key];
}
console.log(summary); // { grade: 'A', name: 'DevPoint', age: 30 }
// 优雅写法
const employee = { name: "DevPoint", age: 30 };
const salary = { grade: "A" };
const summary = { ...employee, ...salary };
console.log(summary); // { name: 'DevPoint', age: 30, grade: 'A' }