如何隱藏所有指定的元素
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:隱藏頁面上所有`<img>`元素?
hide(document.querySelectorAll('img'))
如何檢查元素是否具有指定的類?
頁面DOM里的每個節(jié)點(diǎn)上都有一個classList
對象,程序員可以使用里面的方法新增、刪除、修改節(jié)點(diǎn)上的CSS類。使用classList
,程序員還可以用它來判斷某個節(jié)點(diǎn)是否被賦予了某個CSS類。
const hasClass = (el, className) => el.classList.contains(className)
// 事例
hasClass(document.querySelector('p.special'), 'special') // true
如何切換一個元素的類?
const toggleClass = (el, className) => el.classList.toggle(className)
// 事例 移除 p 具有類`special`的 special 類
toggleClass(document.querySelector('p.special'), 'special')
如何獲取當(dāng)前頁面的滾動位置?
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}
如何平滑滾動到頁面頂部
const scrollToTop = () => {
const c = document.documentElement.scrollTop || document.body.scrollTop;
if (c > 0) {
window.requestAnimationFrame(scrollToTop);
window.scrollTo(0, c - c / 8);
}
}
// 事例
scrollToTop()
window.requestAnimationFrame()
告訴瀏覽器——你希望執(zhí)行一個動畫,并且要求瀏覽器在下次重繪之前調(diào)用指定的回調(diào)函數(shù)更新動畫。該方法需要傳入一個回調(diào)函數(shù)作為參數(shù),該回調(diào)函數(shù)會在瀏覽器下一次重繪之前執(zhí)行。
requestAnimationFrame:
優(yōu)勢:由系統(tǒng)決定回調(diào)函數(shù)的執(zhí)行時機(jī)。60Hz的刷新頻率,那么每次刷新的間隔中會執(zhí)行一次回調(diào)函數(shù),不會引起丟幀,不會卡頓。
如何檢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;
};
// 事例
elementIsVisibleInViewport(el); // 需要左右可見
elementIsVisibleInViewport(el, true); // 需要全屏(上下左右)可以見
如何獲取元素中的所有圖像?
const getImages = (el, includeDuplicates = false) => {
const images = [...el.getElementsByTagName('img')].map(img => img.getAttribute('src'));
return includeDuplicates ? images : [...new Set(images)];
};
// 事例:includeDuplicates 為 true 表示需要排除重復(fù)元素
getImages(document, true); // ['image1.jpg', 'image2.png', 'image1.png', '...']
getImages(document, false); // ['image1.jpg', 'image2.png', '...']
如何確定設(shè)備是移動設(shè)備還是臺式機(jī)/筆記本電腦?
const detectDeviceType = () =>
/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)
? 'Mobile'
: 'Desktop';
// 事例
detectDeviceType(); // "Mobile" or "Desktop"
How to get the current URL?
const currentURL = () => window.location.href
// 事例
currentURL() // 'https://google.com'
如何創(chuàng)建一個包含當(dāng)前URL參數(shù)的對象?
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'); // {}
如何將一組表單元素轉(zhuǎn)化為對象?
const formToObject = form =>
Array.from(new FormData(form)).reduce(
(acc, [key, value]) => ({
...acc,
[key]: value
}),
{}
);
// 事例
formToObject(document.querySelector('#form'));
// { email: 'test@email.com', name: 'Test Name' }
如何從對象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' }] };
// Example
get(obj, 'selector.to.val', 'target[0]', 'target[2].a');
// ['val to select', 1, 'test']
如何在等待指定時間后調(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'
);
// 1秒后打印 'later'
如何在給定元素上觸發(fā)特定事件且能選擇地傳遞自定義數(shù)據(jù)?
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' });
自定義事件的函數(shù)有 Event
、CustomEvent
和 dispatchEvent
// 向 window派發(fā)一個resize內(nèi)置事件
window.dispatchEvent(new Event('resize'))
// 直接自定義事件,使用 Event 構(gòu)造函數(shù):
var event = new Event('build');
var elem = document.querySelector('#id')
// 監(jiān)聽事件
elem.addEventListener('build', function (e) { ... }, false);
// 觸發(fā)事件.
elem.dispatchEvent(event);
tips: 如果是在 iframe 內(nèi)部調(diào)用的話則記得使用 top 替換 window,它代表頂層的窗口。
CustomEvent
可以創(chuàng)建一個更高度自定義事件,還可以附帶一些數(shù)據(jù),具體用法如下:
var myEvent = new CustomEvent(eventname, options);
其中 options 可以是:
{
detail: {
...
},
bubbles: true, //是否冒泡
cancelable: false //是否取消默認(rèn)事件
}
其中 detail
可以存放一些初始化的信息,可以在觸發(fā)的時候調(diào)用。其他屬性就是定義該事件是否具有冒泡等等功能。
內(nèi)置的事件會由瀏覽器根據(jù)某些操作進(jìn)行觸發(fā),自定義的事件就需要人工觸發(fā)。 dispatchEvent
函數(shù)就是用來觸發(fā)某個事件:
element.dispatchEvent(customEvent);
上面代碼表示,在 element
上面觸發(fā) customEvent
這個事件。
// 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);
使用自定義事件需要注意兼容性問題,而使用 jQuery 就簡單多了:
// 綁定自定義事件
$(element).on('myCustomEvent', function(){});
// 觸發(fā)事件
$(element).trigger('myCustomEvent');
// 此外,你還可以在觸發(fā)自定義事件時傳遞更多參數(shù)信息:
$( "p" ).on( "myCustomEvent", function( event, myName ) {
$( this ).text( myName + ", hi there!" );
});
$( "button" ).click(function () {
$( "p" ).trigger( "myCustomEvent", [ "John" ] );
});
如何從元素中移除事件監(jiān)聽器?
const off = (el, evt, fn, opts = false) => el.removeEventListener(evt, fn, opts);
const fn = () => console.log('!');
document.body.addEventListener('click', fn);
off(document.body, 'click', fn);
如何獲得給定毫秒數(shù)的可讀格式?
const formatDuration = ms => {
if (ms < 0) ms = -ms;
const time = {
day: Math.floor(ms / 86400000),
hour: Math.floor(ms / 3600000) % 24,
minute: Math.floor(ms / 60000) % 60,
second: Math.floor(ms / 1000) % 60,
millisecond: Math.floor(ms) % 1000
};
return Object.entries(time)
.filter(val => val[1] !== 0)
.map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`)
.join(', ');
};
// 事例
formatDuration(1001); // '1 second, 1 millisecond'
formatDuration(34325055574);
// '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'
如何對傳遞的URL發(fā)出POST請求?
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);
}
};
// 事例
copyToClipboard('Lorem ipsum');
// 'Lorem ipsum' copied to clipboard
如何確定頁面的瀏覽器選項(xiàng)卡是否聚焦?
const isBrowserTabFocused = () => !document.hidden;
// 事例
isBrowserTabFocused(); // true
如何創(chuàng)建目錄(如果不存在)?
const fs = require('fs');
const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined);
// 事例
createDirIfNotExists('test');
請求、解析響應(yīng)內(nèi)容并下載
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響應(yīng)內(nèi)容并下載
* @param {*} res blob響應(yīng)內(nèi)容
* @param {String} mimeType MIME類型
*/
export function resolveBlob(res, mimeType) {
const aLink = document.createElement('a')
var blob = new Blob([res.data], { type: mimeType })
// //從response的headers中獲取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.docx") 設(shè)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) // 設(shè)置下載文件名稱
document.body.appendChild(aLink)
aLink.click()
document.body.appendChild(aLink)
}
一些JS方法
/**
* 表格時間格式化
*/
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())
}
/**
* 下劃轉(zhuǎn)駝峰
*/
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 '剛剛'
} else if (diff < 3600) {
// less 1 hour
return Math.ceil(diff / 60) + '分鐘前'
} else if (diff < 3600 * 24) {
return Math.ceil(diff / 3600) + '小時前'
} 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() +
'時' +
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() {
// 據(jù)上一次觸發(fā)時間間隔
const last = +new Date() - timestamp
// 上次被包裝函數(shù)被調(diào)用時間間隔 last 小于設(shè)定時間間隔 wait
if (last < wait && last > 0) {
timeout = setTimeout(later, wait - last)
} else {
timeout = null
// 如果設(shè)定為immediate===true,因?yàn)殚_始邊界已經(jīng)調(diào)用過了此處無需調(diào)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
// 如果延時不存在,重新設(shè)定延時
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)
}