js-apis-system-mediaquery.md

# Media Query


> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> The initial APIs of this module are supported since API version 3. Newly added APIs will be marked with a superscript to indicate their earliest API version.


## Modules to Import


```
import mediaquery from '@system.mediaquery';
```


## mediaquery.matchMedia

matchMedia(condition: string): MediaQueryList

Creates a **MediaQueryList** object based on the query condition.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| condition | string | Yes| Query condition.|

**Return value**

| Type| Description|
| -------- | -------- |
| MediaQueryList | Attributes of the **MediaQueryList** object created. For details, see **MediaQueryList** attributes.|

**Example**

```
export default {    
  matchMedia() {        
    var mMediaQueryList = mediaquery.matchMedia('(max-width: 466)');    
  },
}
```

## MediaQueryEvent

Defines a media query event.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| matches | boolean | Yes| Matching result.|

## MediaQueryList

Defines a media query list.

### Attributes

**System capability**: SystemCapability.ArkUI.ArkUI.Full

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| media | string | No| Serialized media query condition. This parameter is read-only.|
| matches | boolean | Yes| Matching result.|

### onchange

onchange?: (matches: boolean) => void

Called when the **matches** value changes.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| matches | boolean | Yes| New **matches** value.|


### MediaQueryList.addListener

addListener(callback: (event: MediaQueryEvent) => void): void

Adds a listener for this **MediaQueryList** object. The listener must be added before **onShow** is called, that is, it must be added in the **onInit** or **onReady** API.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | (event: MediaQueryEvent) => void | Yes| Callback invoked when the matching condition changes.|

**Example**

```
mMediaQueryList.addListener(maxWidthMatch);
```


### MediaQueryList.removeListener

removeListener(callback: (event: MediaQueryEvent) => void): void

Removes the listener for this **MediaQueryList** object.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| callback | (event: MediaQueryEvent) => void) | Yes| Callback invoked when the matching condition changes.|

**Example**

```
mMediaQueryList.removeListener(maxWidthMatch);
```