38 个非常有用的 JavaScript 单行代码汇总

const isDateValid = (...val) => !Number.isNaN(new Date(...val).valueOf());
isDateValid("December 27, 2022 13:14:00");  // true

const dayDif = (date1, date2) => Math.ceil(Math.abs(date1.getTime() - date2.getTime()) / 86400000)


dayDif(new Date("2022-08-27"), new Date("2022-12-25"))  // 120

const dayOfYear = (date) => Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24);
dayOfYear(new Date());   // 239

const timeFromDate = date => date.toTimeString().slice(0, 8);


timeFromDate(new Date(2021, 11, 2, 12, 30, 0));  // 12:30:00
timeFromDate(new Date());  // now time 09:00:00

const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1)
capitalize("hello world")  // Hello world

const reverse = str => str.split('').reverse().join('');
reverse('hello world');   // 'dlrow olleh'

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

const truncateString = (string, length) => string.length < length ? string : `${string.slice(0, length - 3)}...`;
truncateString('Hi, I should be truncated because I am too loooong!', 36)   // 'Hi, I should be truncated because...'

const stripHtml = html => (new DOMParser().parseFromString(html, 'text/html')).body.textContent || '';

const removeDuplicates = (arr) => [... .new Set(arr)];
console.log(removeDuplicates([1, 2, 2, 3, 3, 4, 4, 5, 5, 6]));

const num = [1,2,2,2,5,66,666,55,5]
const name = ["adarsh","gupta","adarsh","raj","ratesh","raj"]
const uniquenum = [... new Set(num)]
// [1,2,5,66,666,55]
const uniquenames = [... new Set(name)
// ["adarsh","gupta","raj","ratesh"]

const isArrayNotEmpty = (arr) => Array.isArray(arr) && 
Object.keys(arr).length > 0; // Examples
isArrayNotEmpty([]); // false
isArrayNotEmpty([1, 2, 3]); // true

const isNotEmpty = arr => Array.isArray(arr) && arr.length > 0;
isNotEmpty([1, 2, 3]);  // true

const merge = (a, b) => a.concat(b);
const merge = (a, b) => [. . a, . . b];

const isEven = num => num % 2 === 0;
isEven(996);

const average = (.. .args) => args.reduce((a, b) => a + b) / args.length;
average(1, 2, 3, 4, 5); // 3

const random = (min, max) => Math.floor(Math.random() * (max — min + 1) + min);
random(1, 50);

const round = (n, d) => Number(Math.round(n + “e” + d) + “e-” + d)
round(1.005, 2) //1.01
round(1.555, 2) //1.56

const rgbToHex = (r, g, b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
rgbToHex(255, 255, 255);  // '#ffffff'

const randomHex = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0")}`;
randomHex();

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

const clearCookies = document.cookie.split(';').forEach(cookie => document.cookie = cookie.replace(/^ +/, '').replace(/=.*/, `=;expires=${new Date(0).toUTCString()};path=/`));

const getSelectedText = () => window.getSelection().toString();
getSelectedText();

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

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

const isTabInView = () => !document.hidden;

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

const scrolledToBottom = () => document.documentElement.clientHeight + window.scrollY >= document.documentElement.scrollHeight;

const redirect = url => location.href = url
redirect("https://www.google.com/")

const showPrintDialog = () => window.print()

const randomstr = Math.random().toString(36).substring(7)

const rev = (str) => str.split("").reverse().join("")

const randomBoolean = () => Math.random() >= 0.5;
randomBoolean();

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

const trueTypeOf = (obj) => Object.prototype.toString.call(obj).slice(8, -1).toLowerCase();
trueTypeOf(‘’); // string
trueTypeOf(0); // number
trueTypeOf(); // undefined
trueTypeOf(null); // null
trueTypeOf({}); // object
trueTypeOf([]); // array
trueTypeOf(0); // number
trueTypeOf(() => {}); // function

const celsiusToFahrenheit = (celsius) => celsius * 9/5 + 32;
const fahrenheitToCelsius = (fahrenheit) => (fahrenheit — 32) * 5/9;
celsiusToFahrenheit(15); // 59
celsiusToFahrenheit(0); // 32
celsiusToFahrenheit(-20); // -4
fahrenheitToCelsius(59); // 15
fahrenheitToCelsius(32); // 0

const isEmpty = obj => Reflect.ownKeys(obj).length === 0 && obj.constructor === Object;

const shuffle = array => array.sort(() => 0.5-Math.random());
//output
shuffle([1,5,2,45])  
[5,2,1,25]

const isDark = window.matchMedia && window.matchMedia(`(prefers-color-scheme:dark)`).match

[var1, var2] = [var2, var1];