aes-gcm-webcrypto.html

<script>  
window.crypto.subtle.generateKey(
    {
        name: "AES-GCM",
        length: 256, //can be  128, 192, or 256
    },
    false, //whether the key is extractable (i.e. can be used in exportKey)
    ["encrypt", "decrypt"] //can "encrypt", "decrypt", "wrapKey", or "unwrapKey"
)
.then(function(key){
    //returns a key object
    console.log(key);
})
.catch(function(err){
    console.error(err);
});
</script>
<script>
//XSS here
window.crypto.subtle.exportKey(
    "jwk", //can be "jwk" or "raw"
    key //extractable must be true
)
.then(function(keydata){
    //returns the exported key data
    console.log(keydata);
})
.catch(function(err){
    console.error(err);
});
</script>