24个解决实际问题的ES6代码段

本文主要是介绍24个解决实际问题的ES6代码段，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

英文 | https://madza.hashnode.dev/24-modern-es6-code-snippets-to-solve-practical-js-problems

作者 | Madza 译者 | 王强策划 | 李俊辰

这篇文章基于实际使用场景总结了 24 个 ES6 代码段，可用来解决项目中可能遇到的一系列问题。

1、如何隐藏所有指定元素？

 const hide = (...el) => [...el].forEach(e => (e.style.display = 'none'));  // Example  hide(document.querySelectorAll('img')); // 隐藏页面上的所有  元素

2、如何确认元素是否具有指定的类？

const hasClass = (el, className) => el.classList.contains(className);  // Example  hasClass(document.querySelector('p.special'), 'special'); // true

3、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、如何获取当前页面的滚动位置？

 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、如何平滑滚动到页面顶部？

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包含子元素？

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')); // false

7、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); // (不完全可见)  elementIsVisibleInViewport(el, true); // (部分可见)

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、如何分辨设备是移动设备还是桌面设备？

const detectDeviceType = () =>  /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)  ? 'Mobile'  : 'Desktop';  // Example  detectDeviceType(); // "Mobile" or "Desktop"

10、如何获取当前 URL？

const currentURL = () => window.location.href;  // Example  currentURL(); // 'https://google.com'

11、如何创建一个包含当前 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、如何从对象中检索给定选择器指示的一组属性？

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、如何在等待一定时间后调用提供的函数（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 page

17、如何获得给定毫秒数的可读格式？

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(', ');  };  // Examples  formatDuration(1001); // '1 second, 1 millisecond'  formatDuration(34325055574); // '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'

18、如何获取两个日期之间的天数间隔？

 const getDaysDiffBetweenDates = (dateInitial, dateFinal) =>  (dateFinal - dateInitial) / (1000 * 3600 * 24);  // Example  getDaysDiffBetweenDates(new Date('2017-12-13'), new Date('2017-12-22')); // 9

19、如何对传递的 URL 进行 GET 请求？

 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、如何对传递的 URL 进行 POST 请求？

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、如何为指定选择器创建具有指定范围、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" 的元素创建一个两秒的计时器

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活跃状态？

const isBrowserTabFocused = () => !document.hidden;  // Example  isBrowserTabFocused(); // true

24、如果一个目录不存在，如何创建它？

 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

本文完~