js数据流之间的转换blobfileDataURLcanvasArrayBuffer

　　将blob转成file
　　利用new File();function blobToFile(blob, filename, type) { 	return new File([blob], filename, { type }) }  blobToFile(＂test info＂, ＂test＂, ＂text/plain＂ )
　　输出如下
　　更进一步了解可阅读MDN File - Web API 鎺ュ彛鍙傝€� | MDNMDN Web DocsMDN logoMozilla logo
　　Blob() - Web API 接口参考 | MDN讲解将file转换成DataURL
　　利用URL.createObjectURL() let img = document.getElementById(＂img＂) let file = document.getElementById(＂file＂) file.onchange = function () { let imgFile = this.files[0] img.src = URL.createObjectURL(imgFile) 	img.onload = function () { 		URL.revokeObjectURL(this.src) 	} }
　　更进一步了解可阅读 MDN URL.createObjectURL() - Web API 鎺ュ彛鍙傝€� | MDNMDN Web DocsMDN logoMozilla logo 讲解利用FileReader.readAsDataURL()let img = document.getElementById(＂img＂) let file = document.getElementById(＂file＂) file.onchange = function (e) { let imgFile = this.files[0] let fileReader = new FileReader() fileReader.readAsDataURL(imgFile)   fileReader.onload = function () {   	img.src = this.result   } }
　　更进一步了解可阅读FileReader - Web API 鎺ュ彛鍙傝€� | MDNMDN Web DocsMDN logoMozilla logo简介将DataURL转成filefunction dataURLToFile (dataUrl, fileName) { const dataArr = dataUrl.split(＂,＂) const mime = dataArr[0].match(/:(.*);/)[1] const originStr = atob(dataArr[1]) 	return new File([originStr], fileName, { type: mime }) } dataURLToFile(＂data:text/plain;base64,YWFhYWFhYQ==＂, ＂测试文件＂) // File {name: ＂测试文件＂, lastModified: 1640784525620, lastModifiedDate: Wed Dec 29 2021 21:28:45 GMT+0800 (中国标准时间), webkitRelativePath: ＂＂, size: 7, …}
　　复杂处理方式如下function dataURLToFile (dataUrl, filename) { const dataArr = dataUrl.split(＂,＂) const mime = dataArr[0].match(/:(.*);/)[1] const originStr = atob(dataArr[1]) let n = originStr.length const u8Arr = new Uint8Array(n)   while (n--) {   	u8Arr[n] = originStr.charCodeAt(n)   } return new File([u8Arr], filename, { type: mime }) } dataURLToFile(＂data:text/plain;base64,YWFhYWFhYQ==＂, ＂测试文件＂) console.log(dataURLToFile(＂data:text/plain;base64,YWFhYWFhYQ==＂,＂测试文件＂)); // File {name: ＂测试文件＂, lastModified: 1640784866937, lastModifiedDate: Wed Dec 29 2021 21:34:26 GMT+0800 (中国标准时间), webkitRelativePath: ＂＂, size: 7, …}
　　将canvas转成DataURL
　　利用canvas.toDataURL()// html  // js document.querySelector(＂#file＂).onchange = function () {   canvasToDataURL(this.files[0]).then(res => console.log(res))  } function canvasToDataURL (file) { return new Promise(resolve => {     const img = document.createElement(＂img＂)     img.src = URL.createObjectURL(file)     img.onload = function () {     const canvas = document.createElement(＂canvas＂)     canvas.width = img.width     canvas.height = img.height     const ctx = canvas.getContext(＂2d＂)     ctx.drawImage(img, 0, 0)     resolve(canvas.toDataURL(＂image/png＂, 1))     } }) }
　　将DataURL转成canvasfunction dataUrlToCanvas (dataUrl) { return new Promise(resolve => {     const img = new Image()     img.src = dataUrl     img.onload = function () {     const canvas = document.createElement(＂canvas＂)     canvas.width = this.width     canvas.height = this.height     const ctx = canvas.getContext(＂2d＂)     ctx.drawImage(this, 0, 0)     resolve(canvas)     } }) } const dataUrl = ＂data:image/png;base64,iVBORw0KGgoAAAANSUh...＂ dataUrlToCanvas(dataUrl) .then(res => document.body.appendChild(res))
　　将canvas转成blob
　　利用canvas.toBlob()
　　// html  // js document.querySelector(＂#file＂).onchange = function () { canvasToDataURL(this.files[0]) .then(res => console.log(res)) } function canvasToDataURL (file) { return new Promise(resolve => {   const img = document.createElement(＂img＂)   img.src = URL.createObjectURL(file)   img.onload = function () {   const canvas = document.createElement(＂canvas＂)   canvas.width = img.width   canvas.height = img.height   const ctx = canvas.getContext(＂2d＂)   ctx.drawImage(img, 0, 0)   canvas.toBlob(function (e) {   	resolve(e)   }, ＂image/png＂, 1) } })
　　将canvas转成file
　　将canvas转成Blob，然后将Blob转成file即可，可看最开始的文件类型转换流程图。
　　或将canvas转成dataURL，然后将dataURL转成file即可，可看最开始的文件类型转换流程图。blob转arrayBuffer
　　利用FileReader.readAsArrayBuffer()function blobToArrayBuffer (blob, callback) { const reader = new FileReader() reader.readAsArrayBuffer(blob) reader.onload = function () { 	callback(this.result) } } let blob = new Blob([1, 2, 3, 4, 5]) blobToArrayBuffer(blob, (arrayBuffer) => { console.log(arrayBuffer) }) // ArrayBuffer(5)
　　arrayBuffer转blob
　　利用new Blob()function arrayBufferToBlob (arrayBuffer, type) { 	return new Blob([arrayBuffer], { type }) } blobToArrayBuffer(new Blob([1, 2, 3, 4, 5]), (arrayBuffer) => { console.log(arrayBufferToBlob(arrayBuffer, ＂text/plain＂)) // Blob {size: 5, type: ＂text/plain＂} })————————————————
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　　原文链接：https://blog.csdn.net/weixin_44116302/article/details/122064841