1. 检查日期是否有效
const isDateValid = (...val) => !Number.isNaN(new Date(...val).valueOf());
isDateValid("December 17, 1995 03:24:00"); // true
2. 计算两个日期之间的间隔
const dayDif = (date1, date2) => Math.ceil(Math.abs(date1.getTime() - date2.getTime()) / 86400000)
dayDif(new Date("2021-11-3"), new Date("2022-2-1")) // 90
3. 查找日期位于一年中的第几天
const dayOfYear = (date) => Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24); dayOfYear(new Date()); // 307
4. 时间格式化hour:minutes:seconds
const timeFromDate = date => date.toTimeString().slice(0, 8); timeFromDate(new Date(2021, 11, 2, 12, 30, 0)); // 12:30:00 timeFromDate(new Date()); // 返回当前时间 09:00:00
5 字符串首字母大写
const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1)
capitalize("hello world") // Hello world
6. 翻转字符串
const reverse = str => str.split('').reverse().join('');
reverse('hello world'); // 'dlrow olleh'
7. 随机字符串
const randomString = () => Math.random().toString(36).slice(2); randomString();
8. 截断字符串
const truncateString = (string, length) => string.length < length ? string : `${string.slice(0, length - 3)}...`;
truncateString('Hi, I should be truncated because I am too loooong!', 36) // 'Hi, I should be truncated because...'
9. 去除字符串中的HTML
const stripHtml = html => (new DOMParser().parseFromString(html, 'text/html')).body.textContent || '';
10. 从数组中移除重复项
const removeDuplicates = (arr) => [...new Set(arr)]; console.log(removeDuplicates([1, 2, 2, 3, 3, 4, 4, 5, 5, 6]));
11. 判断数组是否为空
const isNotEmpty = arr => Array.isArray(arr) && arr.length > 0; isNotEmpty([1, 2, 3]); // true
12. 合并两个数组
const merge = (a, b) => a.concat(b); const merge = (a, b) => [...a, ...b];
13. 判断一个数是奇数还是偶数
const isEven = num => num % 2 === 0; isEven(996);
14. 获得一组数的平均值
const average = (...args) => args.reduce((a, b) => a + b) / args.length; average(1, 2, 3, 4, 5); // 3
15. 获取两个整数之间的随机整数
const random = (min, max) => Math.floor(Math.random() * (max - min + 1) + min); random(1, 50);
16. 指定位数四舍五入
const round = (n, d) => Number(Math.round(n + "e" + d) + "e-" + d) round(1.005, 2) //1.01 round(1.555, 2) //1.56
17. 将RGB转化为十六机制
const rgbToHex = (r, g, b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1); rgbToHex(255, 255, 255); // '#ffffff'
18. 获取随机十六进制颜色
const randomHex = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0")}`;
randomHex();
19. 复制内容到剪切板
const copyToClipboard = (text) => navigator.clipboard.writeText(text);
copyToClipboard("Hello World");
20. 清除所有cookie
const clearCookies = document.cookie.split(';').forEach(cookie => document.cookie = cookie.replace(/^ +/, '').replace(/=.*/, `=;expires=${new Date(0).toUTCString()};path=/`));
21. 获取选中的文本
const getSelectedText = () => window.getSelection().toString(); getSelectedText();
22. 检测是否是黑暗模式
const isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches
console.log(isDarkMode)
23. 滚动到页面顶部
const goToTop = () => window.scrollTo(0, 0); goToTop();
24. 判断当前标签页是否激活
const isTabInView = () => !document.hidden;
25. 判断当前是否是苹果设备
const isAppleDevice = () => /Mac|iPod|iPhone|iPad/.test(navigator.platform); isAppleDevice();
26. 是否滚动到页面底部
const scrolledToBottom = () => document.documentElement.clientHeight + window.scrollY >= document.documentElement.scrollHeight;
27. 重定向到一个URL
const redirect = url => location.href = url
redirect("https://www.ipkd.cn/")
28. 打开浏览器打印框
const showPrintDialog = () => window.print()
29. 随机布尔值
const randomBoolean = () => Math.random() >= 0.5; randomBoolean();
30. 变量交换
[foo, bar] = [bar, foo];
31. 获取变量的类型
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
32. 华氏度和摄氏度之间的转化
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
33. 检测对象是否为空
const isEmpty = obj => Reflect.ownKeys(obj).length === 0 && obj.constructor === Object;
标签： 前端知识
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