反向字符串

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

滾動到頁面頂部

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

刪除數組中的重復項

const removeDuplicate = (arr) => [...new Set(arr)];removeDuplicate([1, 2, 3, 4, 4, 2, 1]);????// [1, 2, 3, 4]

獲取數組中的隨機項

const randomItemArray = (arr) => arr[Math.floor(Math.random(?) * arr.length)];randomItemArray(['a', 'b', 'c', 1, 2, 3]);

獲取數組中的最大項

const maxNumber = (arr, n = 1) => [...arr].sort((a, b) => b - a).slice(0, n);maxNumber([4,9,5,7,2])??????/* 9 */

檢查型號

function isNumber(num) {return !isNaN(parseFloat(num)) && isFinite(num);}isNumber("Hello"); ???/*false*/isNumber(123);??????/*true*/

檢查類型為空

const checkNull = val => val === undefined || val === null;checkNull(123)?????????/* false */checkNull() ??????????/* true */checkNull('hello')?????/* false */

獲取數組中的最小數

const minNumber = (arr, n = 1) => [...arr].sort((a, b) => a - b).slice(0, n);console.log(minNumber([3,5,9,7,1])) ????/*1*/

獲取數組中的平均數

const averageNumber = arr => arr.reduce((a, b) => a + b) / arr.length;averageNumber([1, 2, 3, 4, 5]) ??????/* 3 */

檢查元素的類型

const checkType = v => v === undefined ? 'undefined' : v === null ? 'null' : v.constructor.name.toLowerCase();checkType(true)?????????????/*boolean*/checkType("hello World") ???/*string*/checkType(123) ??????????/*number*/

計算數組中元素的出現次數

const countOccurrences = (arr, val) => arr.reduce((a, v) => (v === val ? a + 1 : a), 0);countOccurrences([1,2,2,4,5,6,2], 2) ?/* S? 2 xu?t hi?n 3 l?n trong array */

使用Javascript獲取當前的URL

const getCurrentURL = () => window.location.href;getCurrentURL() /* https://www.niemvuilaptrinh.com */

大寫字符串中的字母

const capitalizeString = str => str.replace(/b[a-z]/g, char => char.toUpperCase());capitalizeString('niem vui lap trinh'); /* 'Niem Vui Lap Trinh' */

將RGB轉換為16進制

const rgbToHex = (r, g, b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);rgbToHex(52, 45, 125);????/* K?t qu? là: '#342d7d'*/

將數字轉換為數組

const numberToArray = n => [...`${n}`].map(i => parseInt(i));numberToArray(246) /*[2, 4, 6]*/numberToArray(357911)??????/*[3, 5, 7, 9, 1, 1]*/

從HTML中獲取內容

const getTextInHTML = html => (new DOMParser().parseFromString(html, 'text/html')).body.textContent || '';getTextInHTML('<h2>Hello World</h2>'); /*'Hello World'*/

在JS中分配多個變量

var [a,b,c,d] = [1, 2, 'Hello', false];console.log(a,b,c,d)?????/* 1 2 'Hello' false */

空數組

let arr = [1, 2, 3, 4, 5];arr.length = 0;console.log(arr);??????/* K?t qu? : [] */

在JS中復制對象

const obj = {name: "niem vui lap trinh",age: 12};const copyObject = { ...obj };console.log(copyObject); /* {name: 'niem vui lap trinh', age: 12}*/

檢查偶數和奇數

const isEven = num => num % 2 === 0;console.log(isEven(1));????????/*false*/console.log(isEven(2));???????/*true*/

合并兩個或多個數組JS

const arr1 = [1, 2, 3];const arr2 = [4, 5, 6];const arr = arr1.concat(arr2);console.log(arr); ???????/* [1, 2, 3, 4, 5, 6] */

將內容復制到剪貼板

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

從一系列值中選擇一個隨機數

var max = 10;var min = 1;var numRandom = Math.floor(Math.random() * (max - min + 1)) + min;console.log(numRandom)

檢查元素是否聚焦

const elementFocus = (el) => (el === document.activeElement);elementIsInFocus(element);/*if true element is focus*//*if false element is not focus*/

用JS測試蘋果設備

const isAppleDevice =/Mac|iPod|iPhone|iPad/.test(navigator.platform);console.log(isAppleDevice);/*if true element is apple devices **//*if false element is not ?apple devices*/

將字符串轉換為數組

const str = "Hello";const arr = [...str];console.log(arr); ???????/* ['H', 'e', 'l', 'l', 'o'] */

在JS中使用箭頭函數

const sum = function(x, y) {return x + y;};/* arrow function */const sum = (x, y) => x + y;

總結

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