总结了工作中常用的 ES6 代码片段

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"));  // 隐藏页面上所有<img />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

5、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

6、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", "..."]