1、如何暗藏所有指定元素？
const hide = (...el) => [...el].forEach(e => (e.style.display = "none"));// Examplehide(document.querySelectorAll("img")); // 暗藏页面上所有<img />元素2、如何确认元素是否具备指定的类？
const hasClass = (el, className) => el.classList.contains(className); // Example hasClass(document.querySelector("p.special"), "special"); // true3、如何切换元素的类？
const toggleClass = (el, className) => el.classList.toggle(className); // Example toggleClass(document.querySelector( p.special ), special ); // 该段不再有 "special" 类4、如何获取以后页面的滚动地位？
const getScrollPosition = (el = window) => ({ x: el.pageXOffset !== undefined ? el.pageXOffset : el.scrollLeft, y: el.pageYOffset !== undefined ? el.pageYOffset : el.scrollTop }); // Example getScrollPosition(); // {x: 0, y: 200}5、如何评估滚动到页面顶部？
const scrollToTop = () => { const c = document.documentElement.scrollTop || document.body.scrollTop; if (c > 0) { window.requestAnimationFrame(scrollToTop); window.scrollTo(0, c - c / 8); } }; // Example scrollToTop();6、如何确认父元素是否蕴含子元素？
const elementContains = (parent, child) => parent !== child && parent.contains(child); // Examples elementContains(document.querySelector("head"), document.querySelector("title")); // true elementContains(document.querySelector("body"), document.querySelector("body")); // false7、如何确认指定元素是否在视口可见？
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; }; // Examples elementIsVisibleInViewport(el); // (不齐全可见) elementIsVisibleInViewport(el, true); // (局部可见)8、如何获取一个元素内的所有图像？
const getImages = (el, includeDuplicates = false) => { const images = [...el.getElementsByTagName("img")].map(img => img.getAttribute("hide")); return includeDuplicates ? images : [...new Set(images)]; }; // Examples getImages(document, true); // ["image1.jpg", "image2.png", "image1.png", "..."] getImages(document, false); // ["image1.jpg", "image2.png", "..."]9、如何分辨设施是挪动设施还是桌面设施？
const detectDeviceType = () => /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent) ? "Mobile" : "Desktop"; // Example detectDeviceType(); // "Mobile" or "Desktop"10、如何获取以后 URL？
const currentURL = () => window.location.href; // Example currentURL(); // "https://google.com"11、如何创立一个蕴含以后 URL 参数的对象？
const getURLParameters = url => (url.match(/([^?=&]+)(=([^&]*))/g) || []).reduce((a, v) => ((a[v.slice(0, v.indexOf( = ))] = v.slice(v.indexOf( = ) + 1)), a), {}); // Examples getURLParameters("http://url.com/page?n=Adam&s;=Smith"); // {n: "Adam", s: "Smith"} getURLParameters("google.com"); // {}12、如何将一组表单元素编码为一个对象？
const formToObject = form => Array.from(new FormData(form)).reduce((acc, [key, value]) => ({ ...acc, [key]: value }),{}); // Example formToObject(document.querySelector("#form")); // { email: "test@email.com", name: "Test Name" }13、如何从对象检索给定选择器批示的一组属性？
const get = (from, ...selectors) => [...selectors].map(s => s.replace(/[([^[]]*)]/g, ".$1.").split(".").filter(t => t !== "").reduce((prev, cur) => prev && prev[cur], from)); const obj = { selector: { to: { val: "val to select" } }, target: [1, 2, { a: "test" }] }; // Example get(obj, "selector.to.val", "target[0]", "target[2].a"); // ["val to select", 1, "test"]14、如何在期待肯定工夫后调用提供的函数（单位毫秒）？
const delay = (fn, wait, ...args) => setTimeout(fn, wait, ...args); delay(function(text) { console.log(text); }, 1000, "later"); // 一秒后记录 "later"15、如何在给定元素上触发特定事件，且可选传递自定义数据？
const triggerEvent = (el, eventType, detail) => el.dispatchEvent(new CustomEvent(eventType, { detail })); // Examples triggerEvent(document.getElementById("myId"), "click"); triggerEvent(document.getElementById( myId ), "click", { username: "bob" });16、如何移除一个元素的事件侦听器？
const off = (el, evt, fn, opts = false) => el.removeEventListener(evt, fn, opts);const fn = () => console.log("!"); document.body.addEventListener("click", fn); off(document.body, "click", fn); // no longer logs "!" upon clicking on the page17、如何取得给定毫秒数的可读格局？
const formatDuration = ms => { if (ms < 0) ms = -ms; const time = { day: Math.floor(ms / 86400000), hour: Math.floor(ms / 3600000) % 24, minute: Math.floor(ms / 60000) % 60, second: Math.floor(ms / 1000) % 60, millisecond: Math.floor(ms) % 1000 }; return Object.entries(time).filter(val => val[1] !== 0).map(([key, val]) => `${val} ${key}${val !== 1 ? "s" : ""}`).join(","); }; // Examples formatDuration(1001); // 1 second, 1 millisecondformatDuration(34325055574); // 397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds18、如何获取两个日期之间的天数距离？
const getDaysDiffBetweenDates = (dateInitial, dateFinal) => (dateFinal - dateInitial) / (1000 * 3600 * 24); // Example getDaysDiffBetweenDates(new Date("2017-12-13"), new Date("2017-12-22")); // 919、如何对传递的 URL 进行 GET 申请？
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、如何对传递的 URL 进行 POST 申请？
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、如何为指定选择器创立具备指定范畴、步长和持续时间的计时器？
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;}; // Example counter( #my-id , 1, 1000, 5, 2000); // 为 id="my-id" 的元素创立一个两秒的计时器22、如何将一个字符串复制到剪贴板？
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); } }; // Example copyToClipboard( Lorem ipsum ); // Lorem ipsum copied to clipboard.23、如何确定页面的浏览器选项卡是否处于前台沉闷状态？
const isBrowserTabFocused = () => !document.hidden; // Example isBrowserTabFocused(); // true24、如果一个目录不存在，如何创立它？
const fs = require( fs ); const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined); // Example createDirIfNotExists( test ); // creates the directory test , if it doesn t exist