async function updateScreen( targetid , formname )
{
  let d = document.forms[ formname ];
  if( d ){
    try{
      let a ={};
      for( let i = 0; i < d.length ; i += 1 )
        a[ d[ i ].name ] = d[ i ].value;

      let r = await fetch( "/api/" , {
        method: "POST" ,
        body: JSON.stringify( a ) ,
        header: {
          "Content-Type": "application/json"
        }
      });
      let t = await r.text();
      let id = document.getElementById( targetid );
      if( id )
        id.innerHTML = t;
    }
      catch ( err ){
    alert( "Error:" + err );
  }  }
    else
    alert( "フォーム名が見つかりません[" + formname + "]" );}
    function requestPermission() {
    Notification.requestPermission().then((permission) => {
      switch (permission) {
        case 'granted': // 許可
          activatePushServer();
          alert( "通知の許可ありがとうございます。" );
          break;
        case 'denied': // ブロック
        case 'default': // ブロックも許可もなし（xで閉じた）
        default:
          alert( "通知の許可をお願いします" );
          break;
      }
    });
  }

    function checkNotificationPermission()
  {
    if( "Notification" in window )
      return Notification.permission;
    return false;
  }

    function activatePushServer(){
    if ('serviceWorker' in navigator) {
            navigator.serviceWorker.register('service-worker.js', {
        scope: '/',
      })
    }
    else {
            alert('serviceWorker に対応していません。')
    }
        navigator.serviceWorker.ready.then( ( registration ) => {
        alert( "ServiceManagerが有効になりました" );      registration.pushManager.getSubscription().then((subscription) => {
                let server_public_key = urlBase64ToUint8Array( "BK4n23ANz4lxduzs0ACsgKVEQX-xuJrkfqMPjh1941CRrzLMYIdY_-g78eXPkko8ZOj0GrG1mWGqd_EVkPeQH_c" );
                registration.pushManager.subscribe({
          userVisibleOnly: true,
          applicationServerKey: server_public_key
        }).then( (subscription ) => {
                    const endpoint = subscription.endpoint;
          const rawKey = subscription.getKey('p256dh');
          const push_public_key = rawKey ? btoa(String.fromCharCode.apply(null, new Uint8Array(rawKey))) : '';
          const rawAuthSecret = subscription.getKey ? subscription.getKey('auth') : '';
          const push_auth_token = rawAuthSecret ? btoa(String.fromCharCode.apply(null, new Uint8Array(rawAuthSecret))) : '';
                    let a = {
                        COMMAND: "hn714WVeGCZ7HExFIDQl47nWA_SElk9OyTN_KHfomU8,",
            FUNCTION: "T1xV20zUs4lZ4PZbQdR-IygW2nxFTbLoMLyowapET9I,",
                        ENDPOINT: endpoint,
            PUBLICKEY: push_public_key,
            TOKEN: push_auth_token
                      }
                    fetch( "/api/" , {
            method: "POST",
            body: JSON.stringify( a ) ,
            header: {
              "Content-Type": "application/json"
            }
          });
                  }).catch(e => console.log('pushサーバーへの登録に失敗しました。'));
      })
    })
  }
    /** サーバー公開鍵をpushサーバーが求める方式にフォーマットする */
  function urlBase64ToUint8Array(server_public_key) {
    const padding = '='.repeat((4 - server_public_key.length % 4) % 4);
    const base64 = (server_public_key + padding).replace(/\-/g, '+').replace(/_/g, '/');
    const rawData = window.atob(base64);
    const outputArray = new Uint8Array(rawData.length);
    for (let i = 0; i < rawData.length; ++i) {
      outputArray[i] = rawData.charCodeAt(i);
    }
    return outputArray;
  }