10个非常实用的JS工具函数
【摘要】 10个非常实用的JS工具函数
生成一周时间
function getWeekTime(){ return [...new Array(7)].map((j,i)=> new Date(Date.now()+i*8.64e7).toLocaleDateString())}
getWeekTime()// ["2020/2/26", "2020/2/27", "2020/2/28", "2020/2/29", "2020/3/1", "2020/3/2", "2020/3/3"]
类型判断
/** * @param {any} target * @param {string} type * @return {boolean} */function isType(target, type) { let targetType = Object.prototype.toString.call(target).slice(8, -1).toLowerCase() return targetType === type.toLowerCase()}
使用
isType([], 'Array') // trueisType(/\d/, 'RegExp') // trueisType(new Date(), 'Date') // trueisType(function(){}, 'Function') // trueisType(Symbol(1), 'Symbol') // true
对象属性剔除
/** * @param {object} object * @param {string[]} props * @return {object} */function omit(object, props=[]){ let res = {} Object.keys(object).forEach(key=>{ if(props.includes(key) === false){ res[key] = typeof object[key] === 'object' && object[key] !== null ? jsON.parse(jsON.stringify(object[key])): object[key] } }) return res}
使用
let data = { id: 1, title: 'xxx', comment: []}omit(data, ['id']) // {title: 'xxx', comment: []}
日期格式化
/** * @param {string} format * @param {number} timestamp - 时间戳 * @return {string} */function formatDate(format='Y-M-D h:m', timestamp=Date.now()){ let date = new Date(timestamp) let dateInfo = { Y: date.getFullYear(), M: date.getMonth()+1, D: date.getDate(), h: date.getHours(), m: date.getMinutes(), s: date.getSeconds() } let formatNumber = (n) => n > 10 ? n : '0' + n let res = format .replace('Y', dateInfo.Y) .replace('M', dateInfo.M) .replace('D', dateInfo.D) .replace('h', formatNumber(dateInfo.h)) .replace('m', formatNumber(dateInfo.m)) .replace('s', formatNumber(dateInfo.s)) return res}
使用
formatDate() // "2020-2-24 13:44"formatDate('M月D日 h:m') // "2月24日 13:45"formatDate('h:m Y-M-D', 1582526221604) // "14:37 2020-2-24"
性能分析
window.onload = function(){ setTimeout(()=>{ let t = performance.timing, m = performance.memory console.table({ 'DNS查询耗时': (t.domainLookupEnd - t.domainLookupStart).toFixed(0), 'TCP链接耗时': (t.connectEnd - t.connectStart).toFixed(0), 'request请求耗时': (t.responseEnd - t.responseStart).toFixed(0), '解析dom树耗时': (t.domComplete - t.domInteractive).toFixed(0), '白屏时间': (t.responseStart - t.navigationStart).toFixed(0), 'domready时间': (t.domContentLoadedEventEnd - t.navigationStart).toFixed(0), 'onload时间': (t.loadEventEnd - t.navigationStart).toFixed(0), 'js内存使用占比': m ? (m.usedjsHeapSize / m.totaljsHeapSize * 100).toFixed(2) + '%' : undefined }) })}
防抖
function debounce(func, wait = 300){ let timer = null; return function(){ if(timer !== null){ clearTimeout(timer); } timer = setTimeout(fn,wait); }}
/** * @param {function} func - 执行函数 * @param {number} wait - 等待时间 * @param {boolean} immediate - 是否立即执行 * @return {function} */function debounce(func, wait = 300, immediate = false){ let timer, ctx; let later = (arg) => setTimeout(()=>{ func.apply(ctx, arg) timer = ctx = null }, wait) return function(...arg){ if(!timer){ timer = later(arg) ctx = this if(immediate){ func.apply(ctx, arg) } }else{ clearTimeout(timer) timer = later(arg) } }}
let scrollHandler = debounce(function(e){ console.log(e)}, 500)window.onscroll = scrollHandler
节流
/** * @param {function} func - 执行函数 * @param {number} delay - 延迟时间 * @return {function} */function throttle(func, delay){ let timer = null return function(...arg){ if(!timer){ timer = setTimeout(()=>{ func.apply(this, arg) timer = null }, delay) } }}
let scrollHandler = throttle(function(e){ console.log(e)}, 500)window.onscroll = scrollHandler
base64数据导出文件下载
/** * @param {string} filename - 下载时的文件名 * @param {string} data - base64字符串 */function downloadFile(filename, data){ let downloadLink = document.createElement('a'); if ( downloadLink ){ document.body.appendChild(downloadLink); downloadLink.style = 'display: none'; downloadLink.download = filename; downloadLink.href = data; if ( document.createEvent ){ let downloadEvt = document.createEvent('MouseEvents'); downloadEvt.initEvent('click', true, false); downloadLink.dispatchEvent(downloadEvt); } else if ( document.createEventObject ) { downloadLink.fireEvent('onclick'); } else if (typeof downloadLink.onclick == 'function' ) { downloadLink.onclick(); } document.body.removeChild(downloadLink); }}
检测是否为PC端浏览器
function isPCBroswer() { let e = window.navigator.userAgent.toLowerCase() , t = "ipad" == e.match(/ipad/i) , i = "iphone" == e.match(/iphone/i) , r = "midp" == e.match(/midp/i) , n = "rv:1.2.3.4" == e.match(/rv:1.2.3.4/i) , a = "ucweb" == e.match(/ucweb/i) , o = "android" == e.match(/android/i) , s = "windows ce" == e.match(/windows ce/i) , l = "windows mobile" == e.match(/windows mobile/i); return !(t || i || r || n || a || o || s || l)}
识别浏览器及平台
function getPlatformInfo(){ //运行环境是浏览器 let inBrowser = typeof window !== 'undefined'; //运行环境是微信 let inWeex = typeof WXEnvironment !== 'undefined' && !!WXEnvironment.platform; let weexPlatform = inWeex && WXEnvironment.platform.toLowerCase(); //浏览器 UA 判断 let UA = inBrowser && window.navigator.userAgent.toLowerCase(); if(UA){ let platforms = { IE: /msie|trident/.test(UA), IE9: UA.indexOf('msie 9.0') > 0, Edge: UA.indexOf('edge/') > 0, Android: UA.indexOf('android') > 0 || (weexPlatform === 'android'), IOS: /iphone|ipad|ipod|ios/.test(UA) || (weexPlatform === 'ios'), Chrome: /chrome\/\d+/.test(UA) && !(UA.indexOf('edge/') > 0), } for (const key in platforms) { if (platforms.hasOwnProperty(key)) { if(platforms[key]) return key } } }}
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