1# Power Manager 2 3> **NOTE**<br> 4> The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version. 5 6The Power Manager module provides APIs for rebooting and shutting down the system, as well as querying the screen status. 7 8 9## Modules to Import 10 11```js 12import power from '@ohos.power'; 13``` 14 15## System Capability 16 17SystemCapability.PowerManager.PowerManager.Core 18 19 20## power.shutdownDevice 21 22shutdownDevice(reason: string): void 23 24Shuts down the system. 25 26This is a system API and cannot be called by third-party applications. 27 28**Required permission**: ohos.permission.REBOOT 29 30**Parameters** 31 32| Name | Type | Mandatory | Description | 33| ------ | ------ | ---- | ----- | 34| reason | string | Yes | Reason for system shutdown.| 35 36**Example** 37 38```js 39power.shutdownDevice("shutdown_test"); 40console.info('power_shutdown_device_test success') 41``` 42 43 44## power.rebootDevice 45 46rebootDevice(reason: string): void 47 48Reboots the system. 49 50**Required permission**: ohos.permission.REBOOT (to reboot) or ohos.permission.REBOOT_RECOVERY (to reboot and enter the recovery or updater mode) 51 52**Parameters** 53 54| Name | Type | Mandatory | Description | 55| ------ | ------ | ---- | ----- | 56| reason | string | Yes | Reason for system reboot.| 57 58**Example** 59 60```js 61power.rebootDevice("reboot_test"); 62console.info('power_reboot_device_test success') 63``` 64 65 66## power.isScreenOn 67 68isScreenOn(callback: AsyncCallback<boolean>): void 69 70Checks the screen status of the current device. 71 72**Parameters** 73 74| Name | Type | Mandatory | Description | 75| -------- | ---------------------------- | ---- | ---------------------------------------- | 76| callback | AsyncCallback<boolean> | Yes | Callback used to obtain the return value.<br>Return value: The value **true** indicates that the screen is on, and the value **false** indicates the opposite.| 77 78**Example** 79 80```js 81power.isScreenOn((error, screenOn) => { 82 if (typeof error === "undefined") { 83 console.info('screenOn status is ' + screenOn); 84 } else { 85 console.log('error: ' + error); 86 } 87}) 88``` 89 90 91## power.isScreenOn 92 93isScreenOn(): Promise<boolean> 94 95Checks the screen status of the current device. 96 97**Return value** 98| Type | Description | 99| ---------------------- | --------------------------------------- | 100| Promise<boolean> | Promise used to obtain the return value. <br/>Return value: The value **true** indicates that the screen is on, and the value **false** indicates the opposite.| 101 102**Example** 103 104```js 105power.isScreenOn() 106.then(screenOn => { 107 console.info('screenOn status is ' + screenOn); 108}) 109.catch(error => { 110 console.log('error: ' + error); 111}) 112``` 113