> ## 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.onMemoryWarning

> Listen for system memory warning events.

Use this API to listen for system memory warning events. When the system is running low on memory, you can release unnecessary resources to prevent your Mini Program from being terminated.

## Parameters

| Property | Type     | Required | Description                                  |
| -------- | -------- | -------- | -------------------------------------------- |
| callback | Function | Yes      | Callback function when memory warning occurs |

## Callback Parameters

| Property | Type   | Description                                   |
| -------- | ------ | --------------------------------------------- |
| level    | Number | Memory alarm level, only available on Android |

## Memory Warning Levels

iOS devices do not have alarm levels. On Android, two alarm levels exist:

| Level | Constant                       | Description                            |
| ----- | ------------------------------ | -------------------------------------- |
| 10    | `TRIM_MEMORY_RUNNING_LOW`      | Low memory warning (Android only)      |
| 15    | `TRIM_MEMORY_RUNNING_CRITICAL` | Critical memory warning (Android only) |

## Code Example

### Basic Usage

```javascript theme={null}
my.onMemoryWarning((res) => {
  console.log('Memory warning level:', res.level);
});
```

### Release Resources on Warning

```javascript theme={null}
App({
  globalData: {
    cache: {},
    images: []
  },

  onLaunch() {
    my.onMemoryWarning((res) => {
      console.log('Memory warning:', res.level);
      this.releaseMemory(res.level);
    });
  },

  releaseMemory(level) {
    if (level >= 10) {
      // Clear cached data
      this.globalData.cache = {};

      // Clear large image arrays
      this.globalData.images = [];

      console.log('Memory released due to warning');
    }
  }
});
```

### Page-Level Memory Management

```javascript theme={null}
Page({
  data: {
    largeDataSet: [],
    imageUrls: []
  },

  onLoad() {
    my.onMemoryWarning(this.handleMemoryWarning);
    this.loadData();
  },

  handleMemoryWarning(res) {
    if (res.level >= 10) {
      // Keep only essential data
      const essentialData = this.data.largeDataSet.slice(0, 10);
      this.setData({
        largeDataSet: essentialData,
        imageUrls: []
      });

      my.showToast({
        content: 'Cleared cache to free memory'
      });
    }
  },

  onUnload() {
    my.offMemoryWarning(this.handleMemoryWarning);
  }
});
```

<Warning>
  When you receive a memory warning, release unused resources immediately. Failure to do so may result in your Mini Program being terminated by the system.
</Warning>

## Related APIs

<CardGroup cols={2}>
  <Card title="my.offMemoryWarning" icon="xmark" href="/jsapi/device/memory-warning/my.offMemoryWarning">
    Stop listening for warnings
  </Card>

  <Card title="my.getSystemInfo" icon="mobile" href="/jsapi/device/system/my.getSystemInfo">
    Get system information
  </Card>
</CardGroup>