//base64转Blob文件 -start

function dataURItoBlob(base64Data, filename) {

 var arr = base64Data.split(',');

 var mime = arr[0].match(/:(.*?);/)[1];

 var bstr = atob(arr[1]);

 var n = bstr.length;

 var u8arr = new Uint8Array(n);

 while (n--) {

u8arr[n] = bstr.charCodeAt(n);

}

 return new File([u8arr], filename, { type: mime });

}

//base64转Blob文件 -end

最后的new File时报错“File is not defined”