分享 28 个你应该知道的JS 实用小技巧
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2022-01-10 14:35
文 | https://niemvuilaptrinh.medium.com/28-tip-javascript-you-should-know-5c8ca83e4f99
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const stringReverse = str => str.split("").reverse().join("");
stringReverse('hello world'); /*dlrow olleh*/
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const scrollToTop = () => window.scrollTo(0, 0);
scrollToTop();
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const removeDuplicate = (arr) => [...new Set(arr)];
removeDuplicate([1, 2, 3, 4, 4, 2, 1]); // [1, 2, 3, 4]
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const randomItemArray = (arr) => arr[Math.floor(Math.random() * arr.length)];
randomItemArray(['a', 'b', 'c', 1, 2, 3]);
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const maxNumber = (arr, n = 1) => [...arr].sort((a, b) => b - a).slice(0, n);
maxNumber([4,9,5,7,2]) /* 9 */
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function isNumber(num) {
return !isNaN(parseFloat(num)) && isFinite(num);
}
isNumber("Hello"); /*false*/
isNumber(123);/*true*/
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const checkNull = val => val === undefined || val === null;
checkNull(123) /* false */
checkNull() /* true */
checkNull('hello') /* false */
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const minNumber = (arr, n = 1) => [...arr].sort((a, b) => a - b).slice(0, n);
console.log(minNumber([3,5,9,7,1])) /*1*/
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const averageNumber = arr => arr.reduce((a, b) => a + b) / arr.length;
averageNumber([1, 2, 3, 4, 5]) /* 3 */
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/*niemvuilaptrinh.com*/ const checkType = v => v === undefined ? 'undefined' : v === null ? 'null' : v.constructor.name.toLowerCase();
checkType(true) /*boolean*/
checkType("hello World") /*string*/
checkType(123) /*number*/
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const countOccurrences = (arr, val) => arr.reduce((a, v) => (v === val ? a + 1 : a), 0);
countOccurrences([1,2,2,4,5,6,2], 2) /* Số 2 xuất hiện 3 lần trong array */
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const getCurrentURL = () => window.location.href;
getCurrentURL() /* https://www.niemvuilaptrinh.com */
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const capitalizeString = str => str.replace(/b[a-z]/g, char => char.toUpperCase());
capitalizeString('niem vui lap trinh'); /* 'Niem Vui Lap Trinh' */
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const rgbToHex = (r, g, b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
rgbToHex(52, 45, 125); /* Kết quả là: '#342d7d'*/
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const numberToArray = n => [...`${n}`].map(i => parseInt(i));
numberToArray(246) /*[2, 4, 6]*/
numberToArray(357911) /*[3, 5, 7, 9, 1, 1]*/
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const getTextInHTML = html => (new DOMParser().parseFromString(html, 'text/html')).body.textContent || '';
getTextInHTML('<h2>Hello World</h2>'); /*'Hello World'*/
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var [a,b,c,d] = [1, 2, 'Hello', false];
console.log(a,b,c,d) /* 1 2 'Hello' false */
let arr = [1, 2, 3, 4, 5];
arr.length = 0;
console.log(arr); /* Kết quả : [] */
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const obj = {
name: "niem vui lap trinh",
age: 12
};
const copyObject = { ...obj };
console.log(copyObject); /* {name: 'niem vui lap trinh', age: 12}*/
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const isEven = num => num % 2 === 0;
console.log(isEven(1)); /*false*/
console.log(isEven(2)); /*true*/
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const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const arr = arr1.concat(arr2);
console.log(arr); /* [1, 2, 3, 4, 5, 6] */
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const copyTextToClipboard = async (text) => {
await navigator.clipboard.writeText(text)
}
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var max = 10;
var min = 1;
var numRandom = Math.floor(Math.random() * (max - min + 1)) + min;
console.log(numRandom)
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const elementFocus = (el) => (el === document.activeElement);
elementIsInFocus(element);
/*if true element is focus*/
/*if false element is not focus*/
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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*/
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const str = "Hello";
const arr = [...str];
console.log(arr); /* ['H', 'e', 'l', 'l', 'o'] */
/* regular function*/
const sum = function(x, y) {
return x + y;
};
/* arrow function */
const sum = (x, y) => x + y;
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