当ID值处于循环并自动递增时，如何在Javascript中使用getelementByID

问题描述：

I have a table being pulled from MySql through PHP.. The TD in the tables have unique IDs and get autoincremented in a loop.

$i=0;
while($row = mysql_fetch_array($result))

  {     $i = $i+1;
        echo "<tr>";
        echo "<td>" . $row['DRAINNAME'] . "</td>";
        echo "<td id='lat" . $i ."'>" . $row['LATITUDE'] . "</td>";
        echo "<td id='lon" . $i ."'>" . $row['LONGITUDE'] . "</td>";
        echo "<td> <input type='button' onclick='detect_load();' value='Click Me' /><br>
        <div id='divsec". $i ."' style='width: 200px; height: 200px;'></div> </td>";
        echo "</tr>";
  }
echo "</table>";

Im writing a Javascript function which should get values from the unique IDs of the TDs..

  function getLocation(pos) {
      latitude = document.getElementById('lat'+ '<?php echo $i; ?>').innerHTML;
      longitude = document.getElementById('lon'+ '<?php echo $i; ?>').innerHTML;
      load_map();
  }

But the '<?php echo $i; ?>' dosent seem to work.. :( I mean, for example--- If the value of i is 2, then td becomes lat2 and lon2 but in javascript, its not taking those ID values i.e. lat2 and lon2.. its giving an error saying its NULL ..

Here is the full Code if you cannot understand it....

<html>
<head>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script type="text/javascript">
  var latitude = '';
  var longitude = '';

  function getLocation(pos) {
      latitude = document.getElementById('lat'+ <?php echo $i; ?>).innerHTML;
      longitude = document.getElementById('lon'+ <?php echo $i; ?>).innerHTML;
      load_map();
  }
  function unknownLocation(){alert('Could not find location');}


  function detect_load(){
    navigator.geolocation.getCurrentPosition(getLocation, unknownLocation);

  }

  function load_map() { 
    if(latitude == '' || longitude == '')
      return false;
    var latlng = new google.maps.LatLng(latitude, longitude);
    var config = {
      zoom: 11,
      center: latlng,
      mapTypeId: google.maps.MapTypeId.ROADMAP
    };


    var map = new google.maps.Map(document.getElementById('divsec'+ <?php echo $i; ?>),config);

                  var marker = new google.maps.Marker({
                  position: latlng, 
                  map: map, 
                  title:"Your requested location!"
              });

  }
</script>

</head>
<body>

<?php
include 'datalogin.php';

$result = mysql_query("SELECT DRAINNAME, LATITUDE, LONGITUDE FROM draininfo");

echo "<table border='1' name='tab1'>
<tr>
<th>Drain Name</th>
<th>Latitude</th>
<th>Longitude</th>
<th>Show On Map</th>
</tr>";
$i=0;
while($row = mysql_fetch_array($result))

  {     $i = $i+1;
        echo "<tr>";
        echo "<td>" . $row['DRAINNAME'] . "</td>";
        echo "<td id='lat" . $i ."'>" . $row['LATITUDE'] . "</td>";
        echo "<td id='lon" . $i ."'>" . $row['LONGITUDE'] . "</td>";
        echo "<td> <input type='button' onclick='detect_load();' value='Click Me' /><br>
        <div id='divsec". $i ."' style='width: 200px; height: 200px;'></div> </td>";
        echo "</tr>";
  }
echo "</table>";

mysql_close($con);
?>


</body>
</html>

答

Woah, the last question contained a little bit more context.

I would not retrieve the information via DOM. It's better to supply this information directly to the function:

echo "<td id='lat" . $i ."'>" . $row['LATITUDE'] . "</td>";
echo "<td id='lon" . $i ."'>" . $row['LONGITUDE'] . "</td>";
echo "<td> <input type='button' onclick='detect_load(" 
    . $row['LATITUDE'] . ","
    . $row['LONGITUDE'] . "," 
    . "\"divsec" . $i . "\");' value='Click Me' /><br>
<div id='divsec". $i ."' style='width: 200px; height: 200px;'></div> </td>";

And then the Javascript-part - incomplete - but notice how the parameters are passed through to the point where they are needed:

function createGetLocation(latitude, longitude, div) {
    return function(pos) {
        load_map(latitude, longitude, div);
    };
}

function unknownLocation(){alert('Could not find location');}


function detect_load(latitude, longitude, div) {
    var getLocation = createGetLocation(latitude, longitude, div);
    navigator.geolocation.getCurrentPosition(getLocation, unknownLocation);
}

function load_map(latitude, longitude, div) {
    var latlng = new google.maps.LatLng(latitude, longitude);
    var config = {
        zoom: 11,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };

    var map = new google.maps.Map(document.getElementById(div), config
    // and so on...
}

答

From jQuery

for (elem : $("#table-id #tr-id td")){
   $(elem) // you can access your td object here if you have an organized td sequence in each tr
}

答

Because the PHP script and Javascript file are two different things, the variable $i does not carry over.

I'm not exactly sure where you call getLocation from, but I am guessing that pos is the numbered element? If so, then do:

latitude = document.getElementById('lat' + pos).innerHTML;
longitude = document.getElementByid('lon' + pos).innerHTML;
load_map();

If this does not answer your question, please update your question to give us a little more information about where these functions are being called (more specifically, the getLocation function).

当ID值处于循环并自动递增时，如何在Javascript中使用getelementByID

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