servicenow can't convert org.mozilla.javascript.NativeArray to byte

 The error message "can't convert org.mozilla.javascript.NativeArray to byte" typically occurs when working with JavaScript in environments that use the Rhino engine or similar JavaScript interpreters in Java contexts, such as ServiceNow's scripting environment. This environment may not directly support certain JavaScript data types or operations as expected in a standard browser-based JavaScript engine.

Here’s how to handle and convert JavaScript arrays to binary data without encountering such errors, specifically for environments like ServiceNow.

Understanding the Issue

• NativeArray in Rhino: In environments like Rhino (used in ServiceNow), a NativeArray is a JavaScript array object that needs special handling to be converted into Java-compatible types.
• Binary Conversion: The challenge is converting a NativeArray to a byte array or similar structure that can be processed as binary data.

Steps to Handle the Conversion

To combine two Base64 strings in a JavaScript environment like ServiceNow, you can:

1. Decode the Base64 strings into binary data.
2. Convert the binary data to a JavaScript array.
3. Combine the arrays and convert them back to a Base64 string.

Here’s a step-by-step guide to achieve this:

Step 1: Decode Base64 to Binary Data

Since you can’t use atob, you need to manually decode the Base64 strings.

javascript
function decodeBase64(base64) {
    var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
    var output = [];

    var buffer = 0, bitsCollected = 0, value;
    for (var i = 0; i < base64.length; i++) {
        value = chars.indexOf(base64[i]);
        if (value === -1) {
            continue;
        }
        buffer = (buffer << 6) | value;
        bitsCollected += 6;

        if (bitsCollected >= 8) {
            bitsCollected -= 8;
            output.push((buffer >>> bitsCollected) & 0xFF);
        }
    }

    return output;
}

Step 2: Convert Base64 String to JavaScript Array

Decode the Base64 string into a NativeArray.

javascript
var base64String1 = "SGVsbG8s";
var base64String2 = "IHdvcmxkIQ==";

var byteArray1 = decodeBase64(base64String1);
var byteArray2 = decodeBase64(base64String2);

Step 3: Combine the Binary Arrays

Combine the binary arrays into one.

javascript
function combineArrays(arr1, arr2) {
    var combined = [];
    for (var i = 0; i < arr1.length; i++) {
        combined.push(arr1[i]);
    }
    for (var j = 0; j < arr2.length; j++) {
        combined.push(arr2[j]);
    }
    return combined;
}

var combinedArray = combineArrays(byteArray1, byteArray2);

Step 4: Re-encode to Base64

Encode the combined array back to Base64.

javascript
function encodeBase64(array) {
    var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    var output = '';

    for (var i = 0; i < array.length; i += 3) {
        var byte1 = array[i] & 0xFF;
        var byte2 = i + 1 < array.length ? array[i + 1] & 0xFF : 0;
        var byte3 = i + 2 < array.length ? array[i + 2] & 0xFF : 0;

        var triplet = (byte1 << 16) | (byte2 << 8) | byte3;

        output += chars[(triplet >> 18) & 0x3F];
        output += chars[(triplet >> 12) & 0x3F];
        output += (i + 1 < array.length) ? chars[(triplet >> 6) & 0x3F] : '=';
        output += (i + 2 < array.length) ? chars[triplet & 0x3F] : '=';
    }

    return output;
}

var combinedBase64String = encodeBase64(combinedArray);
console.log(combinedBase64String);

Final Solution

Combine the two Base64-encoded strings and convert them back into a single Base64 string without using String, Uint8Array, or atob functions, avoiding NativeArray to byte conversion issues.

javascript
function combineBase64Segments(base64String1, base64String2) {
    var byteArray1 = decodeBase64(base64String1);
    var byteArray2 = decodeBase64(base64String2);
    var combinedArray = combineArrays(byteArray1, byteArray2);
    return encodeBase64(combinedArray);
}

// Example usage
var base64String1 = "SGVsbG8s"; // "Hello,"
var base64String2 = "IHdvcmxkIQ=="; // " world!"

var combinedBase64String = combineBase64Segments(base64String1, base64String2);
console.log(combinedBase64String); // Expected output: "SGVsbG8sIHdvcmxkIQ=="

Conclusion

By decoding Base64 strings to binary, concatenating them, and re-encoding, you can avoid issues related to NativeArray conversion and maintain compatibility with JavaScript environments like ServiceNow. This method ensures that binary data is correctly managed and combined into a valid Base64 string.