Pegar variavel Java e colocar no Javascript

package com.android.sensor;

import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.iid.FirebaseInstanceId;
import com.google.firebase.iid.InstanceIdResult;

import org.apache.cordova.*;

public class MainActivity extends CordovaActivity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        // enable Cordova apps to be started in the background
        Bundle extras = getIntent().getExtras();
        if (extras != null && extras.getBoolean("cdvStartInBackground", false)) {
            moveTaskToBack(true);
        }

        // Set by <content src="index.html" /> in config.xml
        //String token = FirebaseInstanceId.getInstance().getToken();
        //Log.d("TOKEN:",token);
        loadUrl(launchUrl);

        FirebaseInstanceId.getInstance().getInstanceId().addOnSuccessListener(MainActivity.this, new OnSuccessListener<InstanceIdResult>() {
            @Override
            public void onSuccess(InstanceIdResult instanceIdResult) {
                String mToken = instanceIdResult.getToken();
                Log.e("TOKEN:",mToken);
            }
        });



    }

}