JS20 - Documentation

Error handling

JS20 applies automatic error handling inside the run functions of the endpoints. At any time you can throw an error and the user-facing response will have status code 500 with your error message, or a generic "Unknown error" message.

• If you throw error like new Error(message: string) then the message is passed to the client
• If you do not want to expose the error message, just throw a generic new Error() without a message
• If any validation fails for any schema (or the schema itself is invalid), then a validation error is thrown automatically with user-facing details about what you did wrong

app.addEndpoint({
    method: 'GET',
    path: '/error-example',
    outputSchema: sMessage,
    isLoggedIn: true,
    run: async (system) => {
        throw new Error("This error message will be user-facing");
    }
});

Custom error handler

You can apply a custom error handler to catch any errors in the app and decide what to do with them:

async function handleError(error: any): ErrorResponse {
    await saveToMyErrorLoggingService(error);

    return {
        error: "A custom error message",
        code: 408
    };
}

const app = new App({
    handleError,
});

What's happening here?

• We provide an async handleError function to catch all errors
• We log the error to an external service
• We return a custom error response with a message and HTTP status code 408