Question

我正在使用watchPosition方法连续获取坐标。我在showLocation方法中得到了我的纬度和经度。现在我想将我获得的所有纬度和经度存储到数据库中，所以我在showLocation方法中编写了db.transcation。现在我如何从showLocation方法获得动态纬度和经度到populateDB方法。我想在每次更改时存储纬度和经度。

<script type="text/javascript" charset="utf-8">
            document.addEventListener("deviceready", onDeviceReady, false);
            var db = window.openDatabase("GPS", "1.0", "Simple GPS", 500000); //will create database GPS or open it
            function onDeviceReady()
            {
                 var watchID = null;
                 if(navigator.geolocation)
                 {

                     var options = { timeout: 5000, enableHighAccuracy: true };
                     watchID = navigator.geolocation.watchPosition(showLocation, errorHandler, options);
                 }  

              }


          function populateDB(tx) {
              tx.executeSql('CREATE TABLE IF NOT EXISTS location (id INTEGER PRIMARY KEY AUTOINCREMENT, latitude TEXT, longitude TEXT, LastModifiedTime CHAR(30))');
               tx.executeSql('INSERT INTO location(latitude,longitude,LastModifiedTime) VALUES ("-----", "------", datetime('now'))');

             }

           function showLocation(position)
             {    
                  // Getting Lat/Longs from call back method
                  var latitude = position.coords.latitude;
                  var longitude = position.coords.longitude;
                  // Display coordinates in html / screen..
                  document.getElementById("demo").innerHTML="<p>Latitude : " + latitude + "</p><p> Longitude: " + longitude +"</p>";
                  document.getElementById("messageTxt").innerHTML="Latitude : " + latitude + " Longitude: " + longitude;
                  document.getElementById("MailLatlongs").innerHTML="Latitude : " + latitude + " Longitude: " + longitude;

                  db.transaction(populateDB, errorCB, successCB);
                 }
    </script>

Answer 1

我认为你想在事务回调函数中传递参数。如果这是您的问题，请参阅此链接。

how can I pass argument in transaction callback function

Answer 2

尝试将它们分配为全局变量：

var latitude;
var longitude;

function populateDB(tx) {
    tx.executeSql('CREATE TABLE IF NOT EXISTS location (id INTEGER PRIMARY KEY AUTOINCREMENT, latitude TEXT, longitude TEXT, LastModifiedTime CHAR(30))');
    tx.executeSql('INSERT INTO location(latitude,longitude,LastModifiedTime) VALUES ("-----", "------", datetime('now'))');
}

function showLocation(position) {    
    // Getting Lat/Longs from call back method
    latitude = position.coords.latitude;
    longitude = position.coords.longitude;
    // Display coordinates in html / screen..
    document.getElementById("demo").innerHTML="<p>Latitude : " + latitude + "</p><p> Longitude: " + longitude +"</p>";
    document.getElementById("messageTxt").innerHTML="Latitude : " + latitude + " Longitude: " + longitude;
    document.getElementById("MailLatlongs").innerHTML="Latitude : " + latitude + " Longitude: " + longitude;
    db.transaction(populateDB, errorCB, successCB);
}

如果我理解你的问题，它应该有效。

Answer 3

使用setTimeout。对于每个间隔。检查位置是否已更改。如果更改，请将其发送到db。 http://www.w3schools.com/jsref/met_win_settimeout.asp

<script type="text/javascript" charset="utf-8">
      document.addEventListener("deviceready", onDeviceReady, false);
        var db = window.openDatabase("GPS", "1.0", "Simple GPS", 500000); //will create database GPS or open it
        function onDeviceReady()
        {
             var watchID = null;
             if(navigator.geolocation)
             {

                 var options = { timeout: 5000, enableHighAccuracy: true };
                 watchID = navigator.geolocation.watchPosition(showLocation, errorHandler, options);
             }  
             initChecking();

          }
      function initChecking() {
          setTimout(checkLocation, 1000);
      }
      var prevLatitude, prevLngitude;
      function checkLocation() {
          var latitude = position.coords.latitude;
          var longitude = position.coords.longitude;
          if(prevLatitude == latitude || prevLngitude == longitude) {
                    //Code to populateDB
                    prevLatitude = latitude;
                    prevLngitude == longitude;
           }
          initChecking();
      }


      function populateDB(tx) {
          tx.executeSql('CREATE TABLE IF NOT EXISTS location (id INTEGER PRIMARY KEY AUTOINCREMENT, latitude TEXT, longitude TEXT, LastModifiedTime CHAR(30))');
           tx.executeSql('INSERT INTO location(latitude,longitude,LastModifiedTime) VALUES ("-----", "------", datetime('now'))');

         }

       function showLocation(position)
         {    
              // Getting Lat/Longs from call back method
              var latitude = position.coords.latitude;
              var longitude = position.coords.longitude;
              // Display coordinates in html / screen..
              document.getElementById("demo").innerHTML="<p>Latitude : " + latitude + "</p><p> Longitude: " + longitude +"</p>";
              document.getElementById("messageTxt").innerHTML="Latitude : " + latitude + " Longitude: " + longitude;
              document.getElementById("MailLatlongs").innerHTML="Latitude : " + latitude + " Longitude: " + longitude;

              db.transaction(populateDB, errorCB, successCB);
         }
</script>

如何动态地在javascript中将值从一个方法传递到另一个方法？

3 个答案: