Customize the JavaScript (Node) error handler

In a production environment, you will want to have full control and visibility over the errors that are happening in your application, including those that would originate from an Optimizely Feature Experimentation JavaScript (Node) SDK.

The Feature Experimentation SDKs provide default implementations of an error handler in the SDKs. Below is an example of using the default error handler from the SDKs:

const { createInstance, errorHandler } = require("@optimizely/optimizely-sdk");
  
const optimizely = createInstance({
  sdkKey: '<YOUR_SDK_KEY>',
  // the default error handler is a no-op
  errorHandler,
});

However, for additional control and visibility into the errors coming from the Optimizely Feature Experimentation SDK, we recommend implementing your own custom error handler.

With a custom error handler, you can choose what to do with an error, whether it may be as simple as logging the error to console or sending the error to another error monitoring service.

Below is an example of using a custom error handler to log errors to the console:

const { createInstance } = require("@optimizely/optimizely-sdk");
 
/**
 * customErrorHandler
 *
 * Object that has a property `handleError` which will be called
 * when an error is thrown in the SDK.
 */
const customErrorHandler = {
  /**
   * handleError
   *
   * Function which gets called when an error is thrown in the SDK
   * @param {Object} error - error object
   * @param {String} error.message - message of the error
   * @param {String} error.stack - stack trace for the error
   */
  handleError: (error) => {
    console.log('CUSTOM_ERROR_HANDLER');
    console.log('****');
    console.log(`Error Message: ${error.message}`);
    console.log(`Error Stack: ${error.stack}`);
    console.log('****');
  }
}
 
const optimizely = createInstance({
  sdkKey: '<YOUR_SDK_KEY>',
  errorHandler: customErrorHandler,
});