# 学会这20+个JavaScript单行代码，可以让你的代码更加骚气

JenK
English

JavaScript不断发展壮大，

## 01-随机获取布尔值

`Math.random`创建一个介于0和1之间的随机数，然后我们检查它是否大于或小于0.5。

``````const getRandomBoolean = () => Math.random() >= 0.5;

console.log(getRandomBoolean());
// a 50/50 chance of returning true or false``````

## 02-检查日期是否为周末

``````const isWeekend = (date) => [0, 6].indexOf(date.getDay()) !== -1;

console.log(isWeekend(new Date(2021, 4, 14)));
// false (Friday)
console.log(isWeekend(new Date(2021, 4, 15)));
// true (Saturday)``````

## 03-检查数字是偶数还是奇数

``````const isEven = (num) => num % 2 === 0;

console.log(isEven(5));
// false
console.log(isEven(4));
// true``````

## 04-获取数组中的唯一值(数组去重)

``````const uniqueArr = (arr) => [...new Set(arr)];

console.log(uniqueArr([1, 2, 3, 1, 2, 3, 4, 5]));
// [1, 2, 3, 4, 5]``````

## 05-检查变量是否为数组

``````const isArray = (arr) => Array.isArray(arr);

console.log(isArray([1, 2, 3]));
// true
console.log(isArray({ name: 'Ovi' }));
// false
console.log(isArray('Hello World'));
// false``````

## 06-在两个数字之间生成一个随机数

``````const random = (min, max) => Math.floor(Math.random() * (max - min + 1) + min);

console.log(random(1, 50));
// could be anything from 1 - 50``````

## 07-生成随机字符串（唯一ID？）

``````const randomString = () => Math.random().toString(36).slice(2);

console.log(randomString());
// could be anything!!!``````

## 08-滚动到页面顶部

``````const scrollToTop = () => window.scrollTo(0, 0);

scrollToTop();``````

## 09-切换布尔

``````// bool is stored somewhere in the upperscope
const toggleBool = () => (bool = !bool);
//or
const toggleBool = b => !b;``````

## 10-交换两个变量

``[foo, bar] = [bar, foo];``

## 11-计算两个日期之间的天数

``````const daysDiff = (date, date2) => Math.ceil(Math.abs(date - date2) / 86400000);

console.log(daysDiff(new Date('2021-05-10'), new Date('2021-11-25')));
// 199``````

## 12-将文字复制到剪贴板

PS：你可能需要添加检查以查看是否存在`navigator.clipboard.writeText`

``````const copyTextToClipboard = async (text) => {
await navigator.clipboard.writeText(text);
};``````

## 13-合并多个数组的不同方法

PS：我们也可以使用“设置”对象从最终数组中复制任何内容。

``````// Merge but don't remove the duplications
const merge = (a, b) => a.concat(b);
// Or
const merge = (a, b) => [...a, ...b];

// Merge and remove the duplications
const merge = [...new Set(a.concat(b))];
// Or
const merge = [...new Set([...a, ...b])];``````

## 14-获取javascript语言的实际类型

``````const trueTypeOf = (obj) => {
return Object.prototype.toString.call(obj).slice(8, -1).toLowerCase();
};

console.log(trueTypeOf(''));
// string
console.log(trueTypeOf(0));
// number
console.log(trueTypeOf());
// undefined
console.log(trueTypeOf(null));
// null
console.log(trueTypeOf({}));
// object
console.log(trueTypeOf([]));
// array
console.log(trueTypeOf(0));
// number
console.log(trueTypeOf(() => {}));
// function``````

## 15-在结尾处截断字符串

``````const truncateString = (string, length) => {
return string.length < length ? string : `\${string.slice(0, length - 3)}...`;
};

console.log(
truncateString('Hi, I should be truncated because I am too loooong!', 36),
);
// Hi, I should be truncated because...``````

## 16-从中间截断字符串

``````const truncateStringMiddle = (string, length, start, end) => {
return `\${string.slice(0, start)}...\${string.slice(string.length - end)}`;
};

console.log(
truncateStringMiddle(
'A long story goes here but then eventually ends!', // string
25, // 需要的字符串大小
13, // 从原始字符串第几位开始截取
17, // 从原始字符串第几位停止截取
),
);
// A long story ... eventually ends!``````

## 17-大写字符串

``````const capitalize = (str) => str.charAt(0).toUpperCase() + str.slice(1);

console.log(capitalize('hello world'));``````

// Hello world

## 18-检查当前选项卡是否在视图/焦点内

``````const isTabInView = () => !document.hidden;  // Not hidden

isTabInView();``````

// true/false

## 19-检查用户是否在Apple设备上

``````const isAppleDevice = () => /Mac|iPod|iPhone|iPad/.test(navigator.platform);

console.log(isAppleDevice);
// true/false``````

## 20-三元运算符

``````// Longhand
const age = 18;
let greetings;

if (age < 18) {
greetings = 'You are not old enough';
} else {
greetings = 'You are young!';
}

// Shorthand
const greetings = age < 18 ? 'You are not old enough' : 'You are young!';``````

## 21-短路评估速记

``````// Longhand
if (name !== null || name !== undefined || name !== '') {
let fullName = name;
}

// Shorthand
const fullName = name || 'buddy';``````

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