18个有用的JavaScript片段
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2020-08-31 20:21
英文 | https://medium.com/javascript-in-plain-english/18-useful-javascript-snippets-for-common-tasks-you-can-use-from-today-96fa03ce3df6
译文 | https://juejin.im/post/6862577796279959566
如果有人问我,作为一个初学者应该学习什么编程语言,我会推荐 JavaScript,这种强大的语言几乎涉及到编程各个方面 - 前端、后端、web应用程序、桌面应用程序、移动应用程序等等。
这篇文章我将展示18个常用的JavaScript片段,在日常开发工作中,它们为我大大节省了时间。
1. maxItemOfArray
获取数组中的最大数字
const maxItemOfArray = (arr) => arr.sort((a, b) => b - a)[0];
let maxItem = maxItemOfArray([3, 5, 12, 5]);
2. areAllEqual
检查数组的所有项是否相等
const areAllEqual = array => array.every(item => item === array[0]);
let check1 = areAllEqual([3, 5, 2]); // false
let check2 = allEqual([3, 3, 3]); // true
3. averageOf
求给定数字的平均值
const averageOf = (…numbers) => numbers.reduce((a, b) => a + b, 0) / numbers.length;
let average = averageOf(5, 2, 4, 7); // 4.5
4. reverseString
反转一个字符串
const reverseString = str => […str].reverse().join(‘’);
let a = reverseString(‘Have a nice day!’); // !yad ecin a evaH
5. sumOf
求给定数字的和
const sumOf = (…numbers) => numbers.reduce((a, b) => a + b, 0);
let sum = sumOf(5, -3, 2, 1); // 5
6. findAndReplace
在字符串中查找给定的单词,并替换为另一个单词
const findAndReplace = (string, wordToFind, wordToReplace) => string.split(wordToFind).join(wordToReplace);
let result = findAndReplace(‘I like banana’, ‘banana’, ‘apple’); // I like apple
7. RGBToHex
将RGB模式下的颜色转换为十六进制
const RGBToHex = (r, g, b) => ((r << 16) + (g << 8) + b).toString(16).padStart(6, ‘0’);
let hex = RGBToHex(255, 255, 255); // ffffff
8. shuffle
音乐播放器如何随机播放播放项目?
const shuffle = ([…array]) => {
let m = array.length;
while (m) {
const i = Math.floor(Math.random() * m — );
[array[m], array[i]] = [array[i], array[m]];
}
return array;
};
shuffle([5, 4, 3, 6, 20]);
9. removeFalseValues
从数组中删除false值,包括false,undefined,NaN,empty
const removeFalseValues = arr => arr.filter(item => item);
let arr = removeFalseValues([3, 4, false, ‘’, 5, true, undefined, NaN, ‘’]); // [3, 4, 5, true]
10. removeDuplicatedValues
从数组中删除重复的项
const removeDuplicatedValues = array => […new Set(array)];
let arr = removeDuplicatedValues([5, 3, 2, 5, 6, 1, 1, 6]); // [5, 3, 2, 6, 1]
11. getTimeFromDate
以日期对象的字符串形式返回时间
const getTimeFromDate = date => date.toTimeString().slice(0, 8);
let time = getTimeFromDate(new Date()); // 09:46:08
12. capitalizeAllWords
将字符串中所有单词的第一个字母大写
const capitalizeAllWords = str => str.replace(/\b[a-z]/g, char => char.toUpperCase());
let str = capitalizeAllWords(‘i love reading book’); // I Love Reading Book
13. getDayDiff
返回两个日期之间以天为单位的差值
const getDayDiff = (date1, date2) => ((date2 - date1) / (1000 * 3600 * 24));
let diff = getDayDiff(new Date('2020-04-01'), new Date('2020-08-15')); // 136
14. radianToDegree
把弧度转换成角度
const radianToDegree = radian => (radian * 180.0) / Math.PI;
let degree = radianToDegree(2.3); // 131.78
15. isValidJSON
检查给定字符串是否是有效的JSON
const isValidJSON = string => {
try {
JSON.parse(string);
return true;
} catch (error) {
return false;
}
};
let check1 = isValidJSON(‘{“title”: “javascript”, “price”: 14}’); // true
let check2 = isValidJSON(‘{“title”: “javascript”, “price”: 14, sub title}’); // false
16. toWords
将给定的字符串转换为单词数组
const toWords = (string, pattern = /[^a-zA-Z-]+/) => string.split(pattern).filter(item => item);
let words = toWords(‘I want to be come a great programmer’); // [“I”, “want”,“to”, “be”, “come”, “a”, “great”, “programmer”]
17. scrollToTop
位于长页面的底部,并且想快速向上滚动至顶部
const scrollToTop = () => {
const t = document.documentElement.scrollTop || document.body.scrollTop;
if (t > 0) {
window.requestAnimationFrame(scrollToTop);
window.scrollTo(0, t — t / 8);
}
};
18. isValidNumber
验证数字是否有效
const isValidNumber = n => !isNaN(parseFloat(n)) && isFinite(n) && Number(n) === n;
let check1 = isValidNumber(10); // true
let check2 = isValidNumber(‘a’); // false
如果你有自己的有用代码片段,请在下面的评论中告诉我。