### 将base64转换为blob ``` 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 }); } ``` ### 将blob转换为file ``` // 使用 blobToFile(blob, imgName) ``` ``` function(theBlob, fileName){ theBlob.lastModifiedDate = new Date(); theBlob.name = fileName || guid() + '.png'; return theBlob; } function guid() {     return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {         var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);         return v.toString(16);     }); } ```