分享 30 个 JavaScript 单行代码片段，提升你的工作效率

const reversedString = str => str.split('').reverse().join('');
reversedString("Hello World"); // dlroW olleH

const titleCase = sentence => sentence.replace(/\b\w/g, char => char.toUpperCase());
titleCase("hello world"); // Hello World

[a, b] = [b, a];

const isTruthy = num => !!num;
isTruthy(0) // False

const uniqueArray = arr => [...new Set(arr)];
uniqueArray([5,5,2,2,2,4,2]) // [ 5, 2, 4 ]

const truncateString = (str, maxLength) => (str.length > maxLength) ? `${str.slice(0, maxLength)}...` : str;
truncateString("Hello World", 8); // Hello Wo...

const deepClone = obj => JSON.parse(JSON.stringify(obj));

const obj1 = { name: "John", age: 40};
const obj2 = deepClone(obj1);
obj2.age = 20;
console.log(obj1.age); // 40

//This method works for most objects, but it has some limitations. Objects with circular references or functions cannot be converted to JSON, so this method will not work for those types of objects.

const lastIndexOf = (arr, item) => arr.lastIndexOf(item);
lastIndexOf([5, 5, 4 , 2 , 3 , 4], 5) // 1

const mergeArrays = (...arrays) => [].concat(...arrays);
mergeArrays([5, 5, 4], [2 , 3 , 4]) // [5, 5, 4, 2, 3, 4]

const longestWord = sentence => sentence.split(' ').reduce((longest, word) => word.length > longest.length ? word : longest, '');
longestWord("The quick brown fox jumped over the lazy dog") // jumped

const range = (start, end) => [...Array(end - start + 1)].map((_, i) => i + start);
range(5, 15); // [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]

const isEmptyObject = obj => Object.keys(obj).length === 0;
isEmptyObject({}) // true
isEmptyObject({ name: 'John' }) // false

const average = arr => arr.reduce((acc, num) => acc + num, 0) / arr.length;
average([1, 2, 3, 4, 5, 6, 7, 8, 9]) // 5

const objectToQueryParams = obj => Object.entries(obj).map(([key, val]) => `${encodeURIComponent(key)}=${encodeURIComponent(val)}`).join('&');
objectToQueryParams({ page: 2, limit: 10 }) // page=2&limit=10

const factorial = num => num <= 1 ? 1 : num * factorial(num - 1);
factorial(4) // 24

const countVowels = str => (str.match(/[aeiou]/gi) || []).length;
countVowels('The quick brown fox jumps over the lazy dog') // 11

const isValidEmail = email => /^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$/.test(email);
isValidEmail("example@email.com") // true
isValidEmail("example") // false

const removeWhitespace = str => str.replace(/\s/g, '');
removeWhitespace("H el l o") // Hello

const isLeapYear = year => (year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0);
isLeapYear(2023) // false
isLeapYear(2004) // true

const generateRandomString = length => [...Array(length)].map(() => Math.random().toString(36)[2]).join('')
generateRandomString(8) // 4hq4zm7y

const copyToClipboard = (content) => navigator.clipboard.writeText(content)
copyToClipboard("Hello World")

const currentTime = () => new Date().toLocaleTimeString([], { hour: '2-digit', minute: '2-digit', second: '2-digit', hour12: false })
currentTime() // 19:52:21

const isEven = num => num % 2 === 0
isEven(1) // false
isEven(2) // true

const isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches
console.log(isDarkMode) // false

const goToTop = () => window.scrollTo(0, 0)
goToTop()

const isValidDate = date => date instanceof Date && !isNaN(date);
isValidDate(new Date("This is not date.")) // false
isValidDate(new Date("08-10-2023")) // true

const generateDateRange = (startDate, endDate) => Array.from({ length: (endDate - startDate) / (24 * 60 * 60 * 1000) + 1 }, (_, index) => new Date(startDate.getTime() + index * 24 * 60 * 60 * 1000));
generateDateRange(new Date("2023-09-31"), new Date("2023-10-08")) // [Sun Oct 01 2023 05:30:00 GMT+0530 (India Standard Time), Mon Oct 02 2023 05:30:00 GMT+0530 (India Standard Time), Tue Oct 03 2023 05:30:00 GMT+0530 (India Standard Time), Wed Oct 04 2023 05:30:00 GMT+0530 (India Standard Time), Thu Oct 05 2023 05:30:00 GMT+0530 (India Standard Time), Fri Oct 06 2023 05:30:00 GMT+0530 (India Standard Time), Sat Oct 07 2023 05:30:00 GMT+0530 (India Standard Time), Sun Oct 08 2023 05:30:00 GMT+0530 (India Standard Time)]

const dayDiff = (d1, d2) => Math.ceil(Math.abs(d1.getTime() - d2.getTime()) / 86400000)
dayDiff(new Date("2023-10-08"), new Date("1999-04-31")) // 8926

const dayInYear = (d) => Math.floor((d - new Date(d.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24)
dayInYear(new Date('2023/10/08'))// 281

const areArraysEqual = (arr1, arr2) => JSON.stringify(arr1) === JSON.stringify(arr2);
areArraysEqual([1, 2, 3], [4, 5, 6]) // false
areArraysEqual([1, 2, 3], [1, 2, 3]) // false