The update module applies to updates throughout the entire OpenHarmony system, including built-in resources and preset applications, but not third-party applications.
There are two types of updates: SD card update and over the air (OTA) update.
- The SD card update depends on the update packages and SD cards.
- The OTA update depends on the server deployed by the phone manufacturer for managing update packages. The OTA server IP address is passed by the caller. The request interface is fixed and developed by the phone manufacturer.
> The initial APIs of this module are supported since API version 6. Newly added APIs will be marked with a superscript to indicate their earliest API version.
## Modules to Import
```
import wifi from '@ohos.wifi_native_js';
```
## wifi.isWifiActive
isWifiActive(): boolean
Checks whether WLAN is activated.
**Return values**
| Type| Description|
| -------- | ---------------------------- |
| boolean | Returns **true** if WLAN is activated; returns **false** otherwise.|
## wifi.getSignalLevel
getSignalLevel(rssi: number, band: number): number