如何隐藏所有指定的元素
const hide = (...el) => [...el].forEach(e => (e.style.display = 'none'))
ES5 ->
var hide = function hide() {
for (var _len = arguments.length, el = Array(_len), _key = 0; _key < _len; _key++) {
el[_key] = arguments[_key];
}
return [].concat(el).forEach(function (e) {
return e.style.display = 'none';
});
};
// 事例:隐藏页面上所有`![]()
`元素?
hide(document.querySelectorAll('img'))
如何检查元素是否具有指定的类？
页面DOM里的每个节点上都有一个classList对象，程序员可以使用里面的方法新增、删除、修改节点上的CSS类。使用classList，程序员还可以用它来判断某个节点是否被赋予了某个CSS类。
const hasClass = (el, className) => el.classList.contains(className)
// 事例
hasClass(document.querySelector('p.special'), 'special') // true
如何切换一个元素的类?
const toggleClass = (el, className) => el.classList.toggle(className)
// 事例 移除 p 具有类`special`的 special 类
toggleClass(document.querySelector('p.special'), 'special')
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
});
// 事例
getScrollPosition(); // {x: 0, y: 200}
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);
}
}
// 事例
scrollToTop()
window.requestAnimationFrame() 告诉浏览器——你希望执行一个动画，并且要求浏览器在下次重绘之前调用指定的回调函数更新动画。该方法需要传入一个回调函数作为参数，该回调函数会在浏览器下一次重绘之前执行。
requestAnimationFrame： 优势：由系统决定回调函数的执行时机。60Hz的刷新频率，那么每次刷新的间隔中会执行一次回调函数，不会引起丢帧，不会卡顿。
如何检查父元素是否包含子元素？
const elementContains = (parent, child) => parent !== child && parent.contains(child);
// 事例
elementContains(document.querySelector('head'), document.querySelector('title'));
// true
elementContains(document.querySelector('body'), document.querySelector('body'));
// false
如何检查指定的元素在视口中是否可见？
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;
};
// 事例
elementIsVisibleInViewport(el); // 需要左右可见
elementIsVisibleInViewport(el, true); // 需要全屏(上下左右)可以见
如何获取元素中的所有图像？
const getImages = (el, includeDuplicates = false) => {
const images = [...el.getElementsByTagName('img')].map(img => img.getAttribute('src'));
return includeDuplicates ? images : [...new Set(images)];
};
// 事例：includeDuplicates 为 true 表示需要排除重复元素
getImages(document, true); // ['image1.jpg', 'image2.png', 'image1.png', '...']
getImages(document, false); // ['image1.jpg', 'image2.png', '...']
如何确定设备是移动设备还是台式机/笔记本电脑？
const detectDeviceType = () =>
/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)
? 'Mobile'
: 'Desktop';
// 事例
detectDeviceType(); // "Mobile" or "Desktop"
How to get the current URL?
const currentURL = () => window.location.href
// 事例
currentURL() // 'https://google.com'
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),
{}
);
// 事例
getURLParameters('http://url.com/page?n=Adam&s=Smith'); // {n: 'Adam', s: 'Smith'}
getURLParameters('google.com'); // {}
如何将一组表单元素转化为对象？
const formToObject = form =>
Array.from(new FormData(form)).reduce(
(acc, [key, value]) => ({
...acc,
[key]: value
}),
{}
);
// 事例
formToObject(document.querySelector('#form'));
// { email: '[email protected]', name: 'Test Name' }
如何从对象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']
如何在等待指定时间后调用提供的函数？
const delay = (fn, wait, ...args) => setTimeout(fn, wait, ...args);
delay(
function(text) {
console.log(text);
},
1000,
'later'
);
// 1秒后打印 'later'
如何在给定元素上触发特定事件且能选择地传递自定义数据？
const triggerEvent = (el, eventType, detail) =>
el.dispatchEvent(new CustomEvent(eventType, { detail }));
// 事例
triggerEvent(document.getElementById('myId'), 'click');
triggerEvent(document.getElementById('myId'), 'click', { username: 'bob' });
自定义事件的函数有 Event、CustomEvent 和 dispatchEvent
// 向 window派发一个resize内置事件
window.dispatchEvent(new Event('resize'))
// 直接自定义事件，使用 Event 构造函数：
var event = new Event('build');
var elem = document.querySelector('#id')
// 监听事件
elem.addEventListener('build', function (e) { ... }, false);
// 触发事件.
elem.dispatchEvent(event);
tips: 如果是在 iframe 内部调用的话则记得使用 top 替换 window，它代表顶层的窗口。
CustomEvent 可以创建一个更高度自定义事件，还可以附带一些数据，具体用法如下：
var myEvent = new CustomEvent(eventname, options);
其中 options 可以是：
{
detail: {
...
},
bubbles: true, //是否冒泡
cancelable: false //是否取消默认事件
}
其中 detail 可以存放一些初始化的信息，可以在触发的时候调用。其他属性就是定义该事件是否具有冒泡等等功能。
内置的事件会由浏览器根据某些操作进行触发，自定义的事件就需要人工触发。 dispatchEvent 函数就是用来触发某个事件：
element.dispatchEvent(customEvent);
上面代码表示，在 element 上面触发 customEvent 这个事件。
// add an appropriate event listener
obj.addEventListener("cat", function(e) { process(e.detail) });
// create and dispatch the event
var event = new CustomEvent("cat", {"detail":{"hazcheeseburger":true}});
obj.dispatchEvent(event);
使用自定义事件需要注意兼容性问题，而使用 jQuery 就简单多了：
// 绑定自定义事件
$(element).on('myCustomEvent', function(){});
// 触发事件
$(element).trigger('myCustomEvent');
// 此外，你还可以在触发自定义事件时传递更多参数信息：
$( "p" ).on( "myCustomEvent", function( event, myName ) {
$( this ).text( myName + ", hi there!" );
});
$( "button" ).click(function () {
$( "p" ).trigger( "myCustomEvent", [ "John" ] );
});
如何从元素中移除事件监听器?
const off = (el, evt, fn, opts = false) => el.removeEventListener(evt, fn, opts);
const fn = () => console.log('!');
document.body.addEventListener('click', fn);
off(document.body, 'click', fn);
如何获得给定毫秒数的可读格式？
const formatDuration = ms => {
if (ms < 0) ms = -ms;
const time = {
day: Math.floor(ms / 86400000),
hour: Math.floor(ms / 3600000) % 24,
minute: Math.floor(ms / 60000) % 60,
second: Math.floor(ms / 1000) % 60,
millisecond: Math.floor(ms) % 1000
};
return Object.entries(time)
.filter(val => val[1] !== 0)
.map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`)
.join(', ');
};
// 事例
formatDuration(1001); // '1 second, 1 millisecond'
formatDuration(34325055574);
// '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'
如何对传递的URL发出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
);
// {"userId": 1, "id": 1337, "title": "Foo", "body": "bar bar bar"}
如何将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);
}
};
// 事例
copyToClipboard('Lorem ipsum');
// 'Lorem ipsum' copied to clipboard
如何确定页面的浏览器选项卡是否聚焦？
const isBrowserTabFocused = () => !document.hidden;
// 事例
isBrowserTabFocused(); // true
如何创建目录（如果不存在）？
const fs = require('fs');
const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined);
// 事例
createDirIfNotExists('test');
请求、解析响应内容并下载
import axios from 'axios'
import { getToken } from '@/utils/auth'
const mimeMap = {
xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
zip: 'application/zip'
}
const baseUrl = process.env.VUE_APP_BASE_API
export function downLoadZip(str, filename) {
var url = baseUrl + str
axios({
method: 'get',
url: url,
responseType: 'blob',
headers: { 'Authorization': 'Bearer ' + getToken() }
}).then(res => {
resolveBlob(res, mimeMap.zip)
})
}
/**
* 解析blob响应内容并下载
* @param {*} res blob响应内容
* @param {String} mimeType MIME类型
*/
export function resolveBlob(res, mimeType) {
const aLink = document.createElement('a')
var blob = new Blob([res.data], { type: mimeType })
// //从response的headers中获取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.docx") 设置的文件名;
var patt = new RegExp('filename=([^;]+\\.[^\\.;]+);*')
var contentDisposition = decodeURI(res.headers['content-disposition'])
var result = patt.exec(contentDisposition)
var fileName = result[1]
fileName = fileName.replace(/\"/g, '')
aLink.href = URL.createObjectURL(blob)
aLink.setAttribute('download', fileName) // 设置下载文件名称
document.body.appendChild(aLink)
aLink.click()
document.body.appendChild(aLink)
}
一些JS方法
/**
* 表格时间格式化
*/
export function formatDate(cellValue) {
if (cellValue == null || cellValue == "") return "";
var date = new Date(cellValue)
var year = date.getFullYear()
var month = date.getMonth() + 1 < 10 ? '0' + (date.getMonth() + 1) : date.getMonth() + 1
var day = date.getDate() < 10 ? '0' + date.getDate() : date.getDate()
var hours = date.getHours() < 10 ? '0' + date.getHours() : date.getHours()
var minutes = date.getMinutes() < 10 ? '0' + date.getMinutes() : date.getMinutes()
var seconds = date.getSeconds() < 10 ? '0' + date.getSeconds() : date.getSeconds()
return year + '-' + month + '-' + day + ' ' + hours + ':' + minutes + ':' + seconds
}
/**
* 首字母大小
*/
export function titleCase(str) {
return str.replace(/( |^)[a-z]/g, L => L.toUpperCase())
}
/**
* 下划转驼峰
*/
export function camelCase(str) {
return str.replace(/-[a-z]/g, str1 => str1.substr(-1).toUpperCase())
}
/**
* @param {number} time
* @param {string} option
* @returns {string}
*/
export function formatTime(time, option) {
if (('' + time).length === 10) {
time = parseInt(time) * 1000
} else {
time = +time
}
const d = new Date(time)
const now = Date.now()
const diff = (now - d) / 1000
if (diff < 30) {
return '刚刚'
} else if (diff < 3600) {
// less 1 hour
return Math.ceil(diff / 60) + '分钟前'
} else if (diff < 3600 * 24) {
return Math.ceil(diff / 3600) + '小时前'
} else if (diff < 3600 * 24 * 2) {
return '1天前'
}
if (option) {
return parseTime(time, option)
} else {
return (
d.getMonth() +
1 +
'月' +
d.getDate() +
'日' +
d.getHours() +
'时' +
d.getMinutes() +
'分'
)
}
}
/**
* @param {string} url
* @returns {Object}
*/
export function getQueryObject(url) {
url = url == null ? window.location.href : url
const search = url.substring(url.lastIndexOf('?') + 1)
const obj = {}
const reg = /(?&=+)=(?&=*)/g
search.replace(reg, (rs, 1, 2) => {
const name = decodeURIComponent($1)
let val = decodeURIComponent($2)
val = String(val)
obj[name] = val
return rs
})
return obj
}
/**
* @param {string} input value
* @returns {number} output value
*/
export function byteLength(str) {
// returns the byte length of an utf8 string
let s = str.length
for (var i = str.length - 1; i >= 0; i--) {
const code = str.charCodeAt(i)
if (code > 0x7f && code <= 0x7ff) s++
else if (code > 0x7ff && code <= 0xffff) s += 2
if (code >= 0xDC00 && code <= 0xDFFF) i--
}
return s
}
/**
* @param {Array} actual
* @returns {Array}
*/
export function cleanArray(actual) {
const newArray = []
for (let i = 0; i < actual.length; i++) {
if (actual[i]) {
newArray.push(actual[i])
}
}
return newArray
}
/**
* @param {Object} json
* @returns {Array}
*/
export function param(json) {
if (!json) return ''
return cleanArray(
Object.keys(json).map(key => {
if (json[key] === undefined) return ''
return encodeURIComponent(key) + '=' + encodeURIComponent(json[key])
})
).join('&')
}
/**
* @param {string} url
* @returns {Object}
*/
export function param2Obj(url) {
const search = url.split('?')[1]
if (!search) {
return {}
}
return JSON.parse(
'{"' +
decodeURIComponent(search)
.replace(/"/g, '\"')
.replace(/&/g, '","')
.replace(/=/g, '":"')
.replace(/+/g, ' ') +
'"}'
)
}
/**
* @param {string} val
* @returns {string}
*/
export function html2Text(val) {
const div = document.createElement('div')
div.innerHTML = val
return div.textContent || div.innerText
}
/**
* Merges two objects, giving the last one precedence
* @param {Object} target
* @param {(Object|Array)} source
* @returns {Object}
*/
export function objectMerge(target, source) {
if (typeof target !== 'object') {
target = {}
}
if (Array.isArray(source)) {
return source.slice()
}
Object.keys(source).forEach(property => {
const sourceProperty = source[property]
if (typeof sourceProperty === 'object') {
target[property] = objectMerge(target[property], sourceProperty)
} else {
target[property] = sourceProperty
}
})
return target
}
/**
* @param {HTMLElement} element
* @param {string} className
*/
export function toggleClass(element, className) {
if (!element || !className) {
return
}
let classString = element.className
const nameIndex = classString.indexOf(className)
if (nameIndex === -1) {
classString += '' + className
} else {
classString =
classString.substr(0, nameIndex) +
classString.substr(nameIndex + className.length)
}
element.className = classString
}
/**
* @param {string} type
* @returns {Date}
*/
export function getTime(type) {
if (type === 'start') {
return new Date().getTime() - 3600 * 1000 * 24 * 90
} else {
return new Date(new Date().toDateString())
}
}
/**
* @param {Function} func
* @param {number} wait
* @param {boolean} immediate
* @return {*}
*/
export function debounce(func, wait, immediate) {
let timeout, args, context, timestamp, result
const later = function() {
// 据上一次触发时间间隔
const last = +new Date() - timestamp
// 上次被包装函数被调用时间间隔 last 小于设定时间间隔 wait
if (last < wait && last > 0) {
timeout = setTimeout(later, wait - last)
} else {
timeout = null
// 如果设定为immediate===true，因为开始边界已经调用过了此处无需调用
if (!immediate) {
result = func.apply(context, args)
if (!timeout) context = args = null
}
}
}
return function(...args) {
context = this
timestamp = +new Date()
const callNow = immediate && !timeout
// 如果延时不存在，重新设定延时
if (!timeout) timeout = setTimeout(later, wait)
if (callNow) {
result = func.apply(context, args)
context = args = null
}
return result
}
}
/**
* This is just a simple version of deep copy
* Has a lot of edge cases bug
* If you want to use a perfect deep copy, use lodash's _.cloneDeep
* @param {Object} source
* @returns {Object}
*/
export function deepClone(source) {
if (!source && typeof source !== 'object') {
throw new Error('error arguments', 'deepClone')
}
const targetObj = source.constructor === Array ? [] : {}
Object.keys(source).forEach(keys => {
if (source[keys] && typeof source[keys] === 'object') {
targetObj[keys] = deepClone(source[keys])
} else {
targetObj[keys] = source[keys]
}
})
return targetObj
}
/**
* @param {Array} arr
* @returns {Array}
*/
export function uniqueArr(arr) {
return Array.from(new Set(arr))
}
/**
* @returns {string}
*/
export function createUniqueString() {
const timestamp = +new Date() + ''
const randomNum = parseInt((1 + Math.random()) * 65536) + ''
return (+(randomNum + timestamp)).toString(32)
}
/**
* Check if an element has a class
* @param {HTMLElement} elm
* @param {string} cls
* @returns {boolean}
*/
export function hasClass(ele, cls) {
return !!ele.className.match(new RegExp('(\s|^)' + cls + '(\s|$)'))
}
/**
* Add class to element
* @param {HTMLElement} elm
* @param {string} cls
*/
export function addClass(ele, cls) {
if (!hasClass(ele, cls)) ele.className += ' ' + cls
}
/**
* Remove class from element
* @param {HTMLElement} elm
* @param {string} cls
*/
export function removeClass(ele, cls) {
if (hasClass(ele, cls)) {
const reg = new RegExp('(\s|^)' + cls + '(\s|$)')
ele.className = ele.className.replace(reg, ' ')
}
}
export function makeMap(str, expectsLowerCase) {
const map = Object.create(null)
const list = str.split(',')
for (let i = 0; i < list.length; i++) {
map[list[i]] = true
}
return expectsLowerCase
? val => map[val.toLowerCase()]
: val => map[val]
}
export const exportDefault = 'export default '
export const beautifierConf = {
html: {
indent_size: '2',
indent_char: ' ',
max_preserve_newlines: '-1',
preserve_newlines: false,
keep_array_indentation: false,
break_chained_methods: false,
indent_scripts: 'separate',
brace_style: 'end-expand',
space_before_conditional: true,
unescape_strings: false,
jslint_happy: false,
end_with_newline: true,
wrap_line_length: '110',
indent_inner_html: true,
comma_first: false,
e4x: true,
indent_empty_lines: true
},
js: {
indent_size: '2',
indent_char: ' ',
max_preserve_newlines: '-1',
preserve_newlines: false,
keep_array_indentation: false,
break_chained_methods: false,
indent_scripts: 'normal',
brace_style: 'end-expand',
space_before_conditional: true,
unescape_strings: false,
jslint_happy: true,
end_with_newline: true,
wrap_line_length: '110',
indent_inner_html: true,
comma_first: false,
e4x: true,
indent_empty_lines: true
}
}
export function isNumberStr(str) {
return /^[+-]?(0|([1-9]\d*))(.\d+)?$/g.test(str)
}