AES encryption in JavaScript and decryption in Java

I have an existing web service that encrypts and decrypts using AES, now I have to encrypt in the same way as in Java, but in javascript. I've read all the threads about doing this in javascript but haven't found any useful solution yet. Javascript is always encrypted differently and I can't find a reason why.

Here is the existing java code:

public static String encrypt(String data) throws Exception {
    byte[] keyValue = encryptionKey.getBytes();
    Key key = new SecretKeySpec(keyValue, "AES");
    Cipher c = Cipher.getInstance("AES/ECB/PKCS5Padding");
    c.init(Cipher.ENCRYPT_MODE, key);
    byte[] encVal = c.doFinal(data.getBytes());
    String encryptedValue = new BASE64Encoder().encode(encVal);
    return encryptedValue;
}

Here's the javascript code I tend to use, but with a different encryption (CryptoJS):

var encrypted = CryptoJS.AES.encrypt(data, encryptionKey);

or any of the following (GibberishAES):

// Defaults to 256 bit encryption
var encrypted = GibberishAES.enc(data, encryptionKey);
// change the bit encrytion
GibberishAES.size(128);
var encrypted = GibberishAES.enc(data, encryptionKey);
GibberishAES.size(192);
var encrypted = GibberishAES.enc(data, encryptionKey);

I can't change the implementation in Java or the way we do security. Can someone with more experience in this area tell me what I'm doing wrong?