base64格式图片转换成二进制图片文件并支持New File格式兼容性

    data:image/bmp;base64,LASDJFLKAJDFLKASDJFL...很长一大截
    

 function dataURLtoFile(dataurl, filename = 'file') {

    
         let arr = dataurl.split(',')
    
         let mime = arr[0].match(/:(.*?);/)[1]
    
         let suffix = mime.split('/')[1]
    
         let bstr = atob(arr[1])
    
         let n = bstr.length
    
         let u8arr = new Uint8Array(n)
    
         while (n--) {
    
             u8arr[n] = bstr.charCodeAt(n)
    
         }
    
         return new File([u8arr], `${filename}.${suffix}`, {
    
             type: m