在将pdf作为base64字符串转换为字节数组时，输入不是有效的Base-64字符串

Question

After converting a pdf file using Cordova Plugin FileReader and send it to a .Net server, the server throws this error "The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters." on converting the base64 string to byte array.

Java Script Code:

window.resolveLocalFileSystemURL(data, 
function (fileEntry) {
    fileEntry.file(function (fileObj) {
        var reader = new FileReader();
        reader.onloadend = function (evt) {             
            base64StringDocument = evt.target.result;
        };
        reader.readAsDataURL(fileObj);    
    },
    function (error) {
        console.log('get fileEntry error: ' + error.message);
    });
},
function (error) {
  console.log('resolve error: ' + error.message);
});

C# Code:

int startIndexOfBase64 = base64String.IndexOf("base64,") + "base64,".Length;
base64String = base64String.Substring(startIndexOfBase64);

byte[] blob = Convert.FromBase64String(base64String);

Base64 string start:

data:application/pdf;base64,JVBERi0xLjQKMSAwIG9iago8PCAvVHlwZSAvQ2F0YWxvZwovUGFnZXMgMiAwIFIKPj4KZW5kb2JqCjMgMCBvYmoKPDwgL1R5cGUgL1BhZ2UKL1BhcmVudCAyIDAgUgovUmVzb3VyY2VzIDQgMCBSCi9NZWRpYUJveCBbMCAwIDU5NSA4NDJdCi9Db250ZW50cyA1IDAgUgo+PgplbmRvYmoKNCAwIG9iago8PCAvUHJvY1NldCBbL1BERiAvSW

Base64 string end:

wMDIyOTI1NiAwMDAwMCBuDQowMDAwMjI5MzYxIDAwMDAwIG4NCjAwMDAyMjk0MzMgMDAwMDAgbg0KMDAwMDIyOTU5MiAwMDAwMCBuDQowMDAwNDU1MDkwIDAwMDAwIG4NCnRyYWlsZXIKPDwgL1NpemUgMTMKL1Jvb3QgMSAwIFIKPj4Kc3RhcnR4cmVmCjQ1NTE3NwolJUVPRg==

Answer 1

Thanks alot for the comments, but applying the below regular expression over the base64 solved the issue.

window.resolveLocalFileSystemURL(data, 
function (fileEntry) {
    fileEntry.file(function (fileObj) {
        var reader = new FileReader();
        reader.onloadend = function (evt) {            
            base64StringDocument = evt.target.result.match(/,(.*)$/)[1];
        };
        reader.readAsDataURL(fileObj);    
    },
    function (error) {
        console.log('get fileEntry error: ' + error.message);
    });
},
function (error) {
  console.log('resolve error: ' + error.message);
});