HarmonyOS web加载H5页面点击扫码成功后如何将结果返回给前端

scanBarcode.startScanForResult可以返回扫码结果，然后@State去设置返回的结果，参考demo如下

import web_webview from '@ohos.web.webview'
import { scanCore, scanBarcode } from '@kit.ScanKit';
// 导入默认界面需要的日志模块和错误码模块
import { hilog } from '@kit.PerformanceAnalysisKit';
import { BusinessError } from '@kit.BasicServicesKit';

let options: scanBarcode.ScanOptions = {
  scanTypes: [scanCore.ScanType.ALL],
  enableMultiMode: true,
  enableAlbum: true
};

class TestClass {
  Result:string = ""
  // ArkTS h5都用await保障执行顺序
  async scan(): Promise<string> {
    let scanResult = await scanBarcode.startScanForResult(getContext(this), options)
    // 收到扫码结果后返回
    this.Result = scanResult.originalValue
    return scanResult.originalValue;
  }
}

@Entry
@Component
export struct PageWeb {
  readonly webUrl: string | Resource = 'www.huawei.com'
  readonly controller: WebviewController = new web_webview.WebviewController()
  userAgentAlreadySet: boolean = false
  @State customUserAgent?: string = undefined
  @State @Watch("passResult") testObj: TestClass = new TestClass();
  // 返回的结果
  @State results:string = "扫码结果"
  passResult(){
    this.results = this.testObj.Result
  }
  build() {
    if (this.customUserAgent) {
      Column() {
        Text(this.results).fontColor("red")
        Web({ src: $rawfile('index.html'), controller: this.controller })
          .domStorageAccess(true)
          .javaScriptProxy({
            object: this.testObj,
            name: "testObjName",
            methodList: ["scan"],
            controller: this.controller
          })

      }
    }
  }

  aboutToAppear(): void {
    // 模拟异步构建 customUserAgent 过程
    setTimeout(() => this.customUserAgent = 'ua/value', 200)
  }

  applyCustomUserAgent(): void {
    this.userAgentAlreadySet = true
    let defaultUserAgent = this.controller.getUserAgent()
    this.controller.setCustomUserAgent(defaultUserAgent + ' ' + this.customUserAgent)
    this.controller.loadUrl(this.webUrl)
  }

  onBackPress(): boolean | void {
    // 自定义页面返回逻辑
    // if (this.controller.accessBackward()) {
    // this.controller.backward()
    // return true
    // }
    return true;
  }
}