24 個(gè)解決JavaScript實(shí)際問(wèn)題的 ES6 代碼片段
英文 | https://dev.to/madza/20-modern-es6-snippets-to-solve-practical-js-problems-3n83
翻譯 | 楊小愛
const hide = (...el) => [...el].forEach(e => (e.style.display = 'none'));// Examplehide(document.querySelectorAll('img')); // Hides all <img> elements on the page
2、檢查元素是否有指定的類
const hasClass = (el, className) => el.classList.contains(className);// ExamplehasClass(document.querySelector('p.special'), 'special'); // true
3、如何切換元素的類
const toggleClass = (el, className) => el.classList.toggle(className);// ExampletoggleClass(document.querySelector('p.special'), 'special');// The paragraph will not have the 'special' class anymore
4、如何獲取當(dāng)前頁(yè)面的滾動(dòng)位置
const getScrollPosition = (el = window) => ({x: el.pageXOffset !== undefined ? el.pageXOffset : el.scrollLeft,y: el.pageYOffset !== undefined ? el.pageYOffset : el.scrollTop});// ExamplegetScrollPosition(); // {x: 0, y: 200}
5、如何平滑滾動(dòng)到頁(yè)面頂部
const scrollToTop = () => {const c = document.documentElement.scrollTop || document.body.scrollTop;if (c > 0) {window.requestAnimationFrame(scrollToTop);window.scrollTo(0, c - c / 8);}};// ExamplescrollToTop();
6、如何檢查父元素是否包含子元素
const elementContains = (parent, child) => parent !== child && parent.contains(child);// ExampleselementContains(document.querySelector('head'), document.querySelector('title'));// trueelementContains(document.querySelector('body'), document.querySelector('body')); // false
7、如何檢查指定的元素在視口中是否可見
const elementIsVisibleInViewport = (el, partiallyVisible = false) => {const { top, left, bottom, right } = el.getBoundingClientRect();const { innerHeight, innerWidth } = window;return partiallyVisible? ((top > 0 && top < innerHeight) || (bottom > 0 && bottom < innerHeight)) &&((left > 0 && left < innerWidth) || (right > 0 && right < innerWidth)): top >= 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth;};// ExampleselementIsVisibleInViewport(el); // (not fully visible)elementIsVisibleInViewport(el, true); // (partially visible)
8、如何獲取元素內(nèi)的所有圖像
const getImages = (el, includeDuplicates = false) => {const images = [...el.getElementsByTagName('img')].map(img => img.getAttribute('src'));return includeDuplicates ? images : [...new Set(images)];};// ExamplesgetImages(document, true); // ['image1.jpg', 'image2.png', 'image1.png', '...']getImages(document, false); // ['image1.jpg', 'image2.png', '...']
9、如何判斷設(shè)備是移動(dòng)設(shè)備還是臺(tái)式機(jī)/筆記本電腦
const detectDeviceType = () =>/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)? 'Mobile': 'Desktop';// ExampledetectDeviceType(); // "Mobile" or "Desktop"
10、如何獲取當(dāng)前網(wǎng)址
const currentURL = () => window.location.href;// ExamplecurrentURL(); // 'https://google.com'
11、如何創(chuàng)建一個(gè)包含當(dāng)前URL參數(shù)的對(duì)象
const getURLParameters = url =>(url.match(/([^?=&]+)(=([^&]*))/g) || []).reduce((a, v) => ((a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1)), a),{});// ExamplesgetURLParameters('http://url.com/page?n=Adam&s=Smith'); // {n: 'Adam', s: 'Smith'}getURLParameters('google.com'); // {}
12、如何將一組表單元素編碼為一個(gè)對(duì)象
const formToObject = form =>Array.from(new FormData(form)).reduce((acc, [key, value]) => ({...acc,[key]: value}),{});// ExampleformToObject(document.querySelector('#form')); // { email: '[email protected]', name: 'Test Name' }
13、如何從對(duì)象中檢索給定選擇器指示的一組屬性
const get = (from, ...selectors) =>[...selectors].map(s =>s.replace(/\[([^\[\]]*)\]/g, '.$1.').split('.').filter(t => t !== '').reduce((prev, cur) => prev && prev[cur], from));const obj = { selector: { to: { val: 'val to select' } }, target: [1, 2, { a: 'test' }] };// Exampleget(obj, 'selector.to.val', 'target[0]', 'target[2].a'); // ['val to select', 1, 'test']
14、wait（毫秒）后如何調(diào)用提供的函數(shù)
const delay = (fn, wait, ...args) => setTimeout(fn, wait, ...args);delay(function(text) {console.log(text);},1000,'later');// Logs 'later' after one second.
15、如何在給定元素上觸發(fā)特定事件，可選擇傳遞自定義數(shù)據(jù)
const triggerEvent = (el, eventType, detail) =>el.dispatchEvent(new CustomEvent(eventType, { detail }));// ExamplestriggerEvent(document.getElementById('myId'), 'click');triggerEvent(document.getElementById('myId'), 'click', { username: 'bob' });
16、如何從元素中移除事件監(jiān)聽器
const off = (el, evt, fn, opts = false) => el.removeEventListener(evt, fn, opts);const fn = () => console.log('!');document.body.addEventListener('click', fn);off(document.body, 'click', fn); // no longer logs '!' upon clicking on the page
17、如何獲取給定毫秒數(shù)的可讀格式
const formatDuration = ms => {if (ms < 0) ms = -ms;const time = {day: Math.floor(ms / 86400000),hour: Math.floor(ms / 3600000) % 24,minute: Math.floor(ms / 60000) % 60,second: Math.floor(ms / 1000) % 60,millisecond: Math.floor(ms) % 1000};return Object.entries(time).filter(val => val[1] !== 0).map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`).join(', ');};// ExamplesformatDuration(1001); // '1 second, 1 millisecond'formatDuration(34325055574); // '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'
18、如何獲得兩個(gè)日期之間的差異（以天為單位）
const getDaysDiffBetweenDates = (dateInitial, dateFinal) =>(dateFinal - dateInitial) / (1000 * 3600 * 24);// ExamplegetDaysDiffBetweenDates(new Date('2017-12-13'), new Date('2017-12-22')); // 9
19、如何向傳遞的URL發(fā)起GET請(qǐng)求
const httpGet = (url, callback, err = console.error) => {const request = new XMLHttpRequest();request.open('GET', url, true);request.onload = () => callback(request.responseText);request.onerror = () => err(request);request.send();};httpGet('https://jsonplaceholder.typicode.com/posts/1',console.log);// Logs: {"userId": 1, "id": 1, "title": "sample title", "body": "my text"}
20、如何向傳遞的URL發(fā)起POST請(qǐng)求
const httpPost = (url, data, callback, err = console.error) => {const request = new XMLHttpRequest();request.open('POST', url, true);request.setRequestHeader('Content-type', 'application/json; charset=utf-8');request.onload = () => callback(request.responseText);request.onerror = () => err(request);request.send(data);};const newPost = {userId: 1,id: 1337,title: 'Foo',body: 'bar bar bar'};const data = JSON.stringify(newPost);httpPost('https://jsonplaceholder.typicode.com/posts',data,console.log);// Logs: {"userId": 1, "id": 1337, "title": "Foo", "body": "bar bar bar"}
21、如何為指定的選擇器創(chuàng)建一個(gè)指定范圍、步長(zhǎng)和持續(xù)時(shí)間的計(jì)數(shù)器
const counter = (selector, start, end, step = 1, duration = 2000) => {let current = start,_step = (end - start) * step < 0 ? -step : step,timer = setInterval(() => {current += _step;document.querySelector(selector).innerHTML = current;if (current >= end) document.querySelector(selector).innerHTML = end;if (current >= end) clearInterval(timer);}, Math.abs(Math.floor(duration / (end - start))));return timer;};// Examplecounter('#my-id', 1, 1000, 5, 2000); // Creates a 2-second timer for the element with id="my-id"
22、如何將字符串復(fù)制到剪貼板
const copyToClipboard = str => {const el = document.createElement('textarea');el.value = str;el.setAttribute('readonly', '');el.style.position = 'absolute';el.style.left = '-9999px';document.body.appendChild(el);const selected =document.getSelection().rangeCount > 0 ? document.getSelection().getRangeAt(0) : false;el.select();document.execCommand('copy');document.body.removeChild(el);if (selected) {document.getSelection().removeAllRanges();document.getSelection().addRange(selected);}};// ExamplecopyToClipboard('Lorem ipsum'); // 'Lorem ipsum' copied to clipboard.
23、如何判斷頁(yè)面的瀏覽器標(biāo)簽是否有焦點(diǎn)
const isBrowserTabFocused = () => !document.hidden;// ExampleisBrowserTabFocused(); // true
24、如果目錄不存在，如何創(chuàng)建
const fs = require('fs');const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined);// ExamplecreateDirIfNotExists('test'); // creates the directory 'test', if it doesn't exist
寫在最后
以上就是我在工作與學(xué)習(xí)中收集整理下來(lái)的24個(gè)代碼片段，對(duì)我來(lái)講，還是非常有用的，因此，我將它分享出來(lái)，也希望對(duì)您有所幫助。
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