Troubleshooting
Common issues and debugging tips
Common Issues
Solutions to frequent problems
shift2appjs is undefined
This means your code is running in a regular browser, not inside the Shift2App wrapper.
Solutions:
- Test your app on a real device or emulator
- Always check if shift2appjs exists before using it
- Provide fallback behavior for browser testing
// Always check first
if (typeof shift2appjs !== "undefined") {
shift2appjs.showToast("Native!");
} else {
alert("Browser fallback");
}Callback function not being called
Callback functions must be defined in the global scope.
// ❌ Wrong - function not accessible
function init() {
function onResult(success) { } // Local scope
shift2appjs.authenticate("onResult"); // Won't work
}
// ✅ Correct - global function
window.onResult = function(success) {
console.log(success);
};
shift2appjs.authenticate("onResult");Ads not showing
Check the following:
- AdMob is enabled in your dashboard
- Valid AdMob App ID is configured
- Ad Unit IDs are correct
- Wait for ads to load: check
isInterstitialAdReady() - Test with test ad IDs first
Push notifications not received
Troubleshooting steps:
- Verify notifications are enabled in dashboard
- Check google-services.json is configured
- Ensure FCM token is registered:
shift2appjs.registerFCMToken(userId) - Check your server is sending to the correct token
- Verify notification permissions on device
Biometric authentication fails
Check the following:
- Device has fingerprint/face hardware
- User has enrolled biometrics in device settings
- Check availability first:
shift2appjs.isBiometricAvailable()
Debugging Tips
How to debug your integration
1. Use Console Logging
// Log all shift2appjs calls
const originalShowToast = shift2appjs.showToast;
shift2appjs.showToast = function(msg) {
console.log("[shift2appjs.showToast]", msg);
return originalShowToast.call(this, msg);
};
// Log return values
function debugCall(method, ...args) {
console.log(`[shift2appjs.${method}]`, args);
const result = shift2appjs[method](...args);
console.log(`[shift2appjs.${method}] returned:`, result);
return result;
}2. Check Function Availability
// List all available functions
if (typeof shift2appjs !== "undefined") {
const functions = Object.getOwnPropertyNames(shift2appjs)
.filter(prop => typeof shift2appjs[prop] === "function");
console.log("Available functions:", functions);
}3. Android Studio Logcat
Use Android Studio's Logcat to see native logs. Filter by your app's package name.
Frequently Asked Questions
Can I use shift2appjs in an iframe?
Yes, shift2appjs is injected into all frames. However, for security, some functions may be restricted in iframes from different origins.
Does shift2appjs work offline?
Most shift2appjs functions work offline (storage, device info, UI). Network-dependent features like FCM registration require connectivity.
Can I add custom native functions?
The current version has a fixed set of functions. Contact support for custom development needs.
Is my data secure?
Data stored via shift2appjs.setItem() is saved in the app's private storage, not accessible to other apps. For sensitive data, use biometric authentication.