> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rebellapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# my.onError

> Listen for JavaScript errors that occur during Mini Program execution.

Use this API to listen for JavaScript errors that occur during Mini Program execution. This allows you to implement custom error handling and logging strategies.

## Parameters

| Property | Type     | Required | Description                             |
| -------- | -------- | -------- | --------------------------------------- |
| callback | Function | Yes      | Handler executed when a JS error occurs |

## Callback Parameters

| Property | Type   | Description       |
| -------- | ------ | ----------------- |
| error    | String | The error message |

## Code Example

### Basic Error Handling

```javascript theme={null}
App({
  onLaunch() {
    my.onError((error) => {
      console.error('JS Error:', error);
    });
  }
});
```

### Error Logging Service

```javascript theme={null}
App({
  onLaunch() {
    my.onError((error) => {
      // Log error to analytics service
      this.logError(error);
    });
  },

  logError(error) {
    my.request({
      url: 'https://api.example.com/errors',
      method: 'POST',
      data: {
        error: error,
        timestamp: Date.now(),
        appId: my.getAppIdSync().appId
      }
    });
  }
});
```

### Page-Level Error Handling

```javascript theme={null}
Page({
  onShow() {
    my.onError((error) => {
      console.warn('Error on page:', error);

      // Show user-friendly message
      my.showToast({
        content: 'Something went wrong',
        type: 'fail'
      });
    });
  },

  onHide() {
    my.offError();
  }
});
```

## Use Cases

<AccordionGroup>
  <Accordion title="Error Monitoring">
    ```javascript theme={null}
    App({
      onLaunch() {
        my.onError((error) => {
          // Send to monitoring service
          this.sendToMonitoring({
            type: 'js_error',
            message: error,
            page: getCurrentPages().pop()?.route,
            time: new Date().toISOString()
          });
        });
      }
    });
    ```
  </Accordion>

  <Accordion title="Development Debugging">
    ```javascript theme={null}
    App({
      onLaunch() {
        my.getRunScene({
          success: ({ envVersion }) => {
            if (envVersion === 'develop') {
              my.onError((error) => {
                // Show detailed error in development
                my.alert({
                  title: 'Debug Error',
                  content: error
                });
              });
            }
          }
        });
      }
    });
    ```
  </Accordion>

  <Accordion title="Error Recovery">
    ```javascript theme={null}
    App({
      onLaunch() {
        my.onError((error) => {
          // Attempt to recover from known errors
          if (error.includes('network')) {
            my.showToast({
              content: 'Network error. Retrying...',
              type: 'fail'
            });
            // Retry logic
          }
        });
      }
    });
    ```
  </Accordion>
</AccordionGroup>

<Info>
  The `my.onError` callback triggers at the same time as the `onError()` method in app registration, with the same parameters.
</Info>

<Warning>
  Currently, this API only captures JavaScript errors. Native errors and other types of exceptions may not be captured.
</Warning>

## Related APIs

<CardGroup cols={2}>
  <Card title="my.offError" icon="xmark" href="/jsapi/event/my.offError">
    Stop listening for error events
  </Card>

  <Card title="my.onUnhandledRejection" icon="exclamation-triangle" href="/jsapi/event/my.onUnhandledRejection">
    Listen for unhandled Promise rejections
  </Card>
</CardGroup>