``` /** * 网络图像文件转Base64 */ function getBase64Image(img) { var canvas = document.createElement("canvas"); canvas.width = img.width; canvas.height = img.height; var ctx = canvas.getContext("2d"); ctx.drawImage(img, 0, 0, img.width, img.height); var ext = img.src.substring(img.src.lastIndexOf(".") + 1).toLowerCase(); var dataURL = canvas.toDataURL("image/" + ext); return dataURL; } /** *Base64字符串转二进制 */ function dataURLtoBlob(dataurl) { var 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 }); } var img = "图像文件URL地址"; var image = new Image(); image.src = img; image.onload = function() { //这样就获取到了文件的Base64字符串 var base64 = getBase64Image(image); //Base64字符串转二进制 var file = dataURLtoBlob(base64); } /** *blob字符串转Base64 */ function blobToDataURL(blob, callback) { var a = new FileReader(); a.onload = function (e) { callback(e.target.result); } a.readAsDataURL(blob); } ```