my.setKeepScreenOn

<!-- API-DEMO page/API/screen/screen.axml-->
<view class="page">
  <view class="page-description">Screen brightness API</view>
  <view class="page-section">
    <view class="page-section-title">Set whether to keep screen on</view>
    <view class="page-section-demo">
      <switch checked="{{status}}" onChange="switchKeepScreenOn"/>
    </view>
  </view>
  <view class="page-section">
    <view class="page-section-title">Set screen brightness</view>
    <view class="page-section-demo">
      <slider value="{{brightness}}" max="1" min="0" onChange="sliderChange" step="0.02"/>
    </view>
  </view>
  <view class="page-section">
    <view class="page-section-title">Get screen brightness</view>
    <view class="page-section-demo">
      <button type="primary" onTap="getBrightness">Get screen brightness</button>
    </view>
  </view>
</view>

// API-DEMO page/API/screen/screen.js
Page({
  data: {
    status: false,
    brightness: 1,
  },
  onLoad() {
    my.getScreenBrightness({
      success: res => {
        this.setData({
          brightness: res.brightness
        })
      },
    })
  },
  sliderChange(e) {
    my.setScreenBrightness({
      brightness: e.detail.value,
      success: (res) => {
        this.setData({
          brightness: e.detail.value,
        })
      }
    })
  },
  switchKeepScreenOn(e) {
    my.setKeepScreenOn({
      keepScreenOn: e.detail.value,
      success: (res) => {
        this.setData({
          status: e.detail.value,
        })
      }
    })
  },
  getBrightness() {
    my.getScreenBrightness({
      success: res => {
        my.alert({
          content: `Current screen brightness: ${res.brightness}`
        });
      }
    })
  }
});