JavaScript常用工具函数汇总（浏览器环境）

 /** * file转为base64 * @param {*} file file对象 * @param {*} callback */ export const fileToDataURL = (file, callback) => { let freader = new FileReader(); freader.readAsDataURL(file); freader.onload = function (e) { callback(e.target.result); } }

 /** * blob流转换为base64 * @param {*} blob blob对象 * @param {*} callback */ export const blobToDataURL = (blob, callback) => { let freader = new FileReader(); freader.readAsDataURL(blob); freader.onload = function (e) { callback(e.target.result); } }

 /** * base64转换为blob * @param {*} dataurl base64 */ export const dataURLtoBlob = (dataurl) => { let arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1], bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n); while (n--) { u8arr[n] = bstr.charCodeAt(n); } return new Blob([u8arr], { type: mime }); }

 /** * 将base64转换为file,IE低版本不兼容 * @param {*} dataurl base64 * @param {*} filename 文件名 */ export const dataURLtoFile = (dataurl, filename) => { let arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1], bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n); while (n--) { u8arr[n] = bstr.charCodeAt(n); } return new File([u8arr], filename, { type: mime }); }

 /** * 图片url转化成base64 * @param {*} url 图片url * @param {*} callback * @param {*} outputFormat 图片格式 */ export const imgUrlToDataURL = (url, callback, outputFormat) => { let canvas = document.createElement('canvas'), ctx = canvas.getContext('2d'), img = new Image; img.crossOrigin = 'Anonymous'; img.src = url + "?timeStamp=" + new Date().getTime(); img.onload = function () { canvas.height = img.height; canvas.width = img.width; // ctx.drawImage(img, 0, 0); ctx.drawImage(this, 0, 0, img.width, img.height); let dataURL = canvas.toDataURL(outputFormat || 'image/png'); // callback.call(this, dataURL); callback && callback(dataURL) canvas = null; }; }

 export function getViewportSize() { let w = 0; let h = 0; if (window.innerWidth) { w = window.innerWidth h = window.innerHeight } else if (document.body && document.body.clientWidth) { w = document.body.clientWidth h = document.body.clientHeight } else if (document.documentElement && document.documentElement.clientWidth) { w = document.documentElement.clientWidth h = document.documentElement.clientHeight } return { w, h } }

 const ua = window.navigator.userAgent.toLowerCase() // 是否微信 export const isWx = () => ua.match(/MicroMessenger/i) == 'micromessenger' // 是否ipad export const isIpad = () => ua.indexOf('ipad') > -1 // 是否iphone export const isIphone = () => ua.indexOf('iphone os') > -1 // 是否uc export const isUc = () => ua.indexOf('ucweb') > -1 // 是否windows pc export const isWindows = () => ua.indexOf('windows') > -1 // 是否android export const isAndroid = () => ua.indexOf('android') > -1 || ua.indexOf('adr') > -1 // 是否ios export const isIos = () => /(iphone|ipod|ipad|ios)/i.test(ua) // 是否qq浏览器 export const isQq = () => ua.indexOf('mqqbrowser') > -1 && ua.indexOf(' qq') <0> ua.indexOf(' qq') > -1 && ua.indexOf('mqqbrowser') <0

 // 开启全屏 export function launchFullscreen(element) { element = element || document.documentElement if (element.requestFullscreen) { element.requestFullscreen() } else if (element.mozRequestFullScreen) { element.mozRequestFullScreen() } else if (element.msRequestFullscreen) { element.msRequestFullscreen() } else if (element.webkitRequestFullscreen) { element.webkitRequestFullScreen() } } // 关闭全屏 export function exitFullscreen() { if (document.exitFullscreen) { document.exitFullscreen() } else if (document.msExitFullscreen) { document.msExitFullscreen() } else if (document.mozCancelFullScreen) { document.mozCancelFullScreen() } else if (document.webkitExitFullscreen) { document.webkitExitFullscreen() } }

 /** * @param {*} number 距离页面顶部的距离 * @param {*} time 滚动所需时间 单位ms */ const scrolling = (number = 0, time) => { if (!time) { document.body.scrollTop = document.documentElement.scrollTop = number; return number; } // 设置循环的间隔时间 值越小消耗性能越高 const spacingTime = 20; // 计算循环的次数 let spacingInex = time / spacingTime; // 获取当前滚动条位置 let nowTop = document.body.scrollTop + document.documentElement.scrollTop; // 计算每次滑动的距离 let everTop = (number - nowTop) / spacingInex; let scrollTimer = setInterval(() => { if (spacingInex > 0) { spacingInex--; ScrollTop(nowTop += everTop); } else { clearInterval(scrollTimer); // 清除计时器 } }, spacingTime); }; // 滚动到距离页面顶部500px的位置 动画时间为300ms // scrolling(500, 300);

 // 运用了H5的scrollIntoView方法，这是一个实验中的功能，IE 8以下、Safari 6以下、Safari on iOS 5以下不兼容 const scrollToAnchor = (anchorName) => { if (anchorName) { // 找到锚点 let anchorElement = document.getElementById(anchorName); // 如果对应id的锚点存在，就跳转到锚点 if (anchorElement) { anchorElement.scrollIntoView({ behavior: 'auto', // 定义动画过渡效果， "auto"或 "smooth" 之一。默认为 "auto" block: 'start', // 定义垂直方向的对齐， "start", "center", "end", 或 "nearest"之一。默认为 "start" inline: 'nearest', // 定义水平方向的对齐， "start", "center", "end", 或 "nearest"之一。默认为 "nearest" }); } } }