navigator.geolocation.watchPosition - frequency

javascript html geolocation

20,382

Solution 1

The spec makes no mention of a frequency option which suggests that this parameter is being ignored. W3C Geolocation spec

Solution 2

You code seems to be working fine: http://jsfiddle.net/Mgk9J/1/

I tested it in Android and when I move the cellphone new lines came up. However in chrome desktop it plots new lines when I change tabs even though they're identical to the last ones, according to the spec this isn't the correctly behavior.

It makes a bit of sense for the desktop version do not plot new lines anyway, the computer isn't moving so new success calbacks execution should not be fired.

<html><head>
  <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  <title> - jsFiddle demo</title>

  <script type="text/javascript" src="/js/lib/dummy.js"></script>




  <link rel="stylesheet" type="text/css" href="/css/result-light.css">

  <style type="text/css">

  </style>



<script type="text/javascript">//<![CDATA[ 
window.onload=function(){
    var watchID = null;

    // PhoneGap is ready
    //
    function f() {
        // Update every 1 ms seconds
        var options = {enableHighAccuracy: true,timeout: 5000,maximumAge: 0,desiredAccuracy: 0, frequency: 1 };
        watchID = navigator.geolocation.watchPosition(onSuccess, onError, options);
    }

    // onSuccess Geolocation
    //
    function onSuccess(position) {

        var str = 'Latitude: '  + position.coords.latitude      + '<br>' +
                  'Longitude: ' + position.coords.longitude     + '<br>' +
                  'Timestamp: ' + position.timestamp     + '<br>\r\n' ;
        document.getElementById('result').value += str;
    }

    // clear the watch that was started earlier
    // 
    function clearWatch() {
        if (watchID != null) {
            navigator.geolocation.clearWatch(watchID);
            watchID = null;
        }
    }

    // onError Callback receives a PositionError object
    //
    function onError(error) {
      alert('code: '    + error.code    + '\n' +
            'message: ' + error.message + '\n');
    }

    document.getElementById('button').addEventListener('click', f);
}//]]>  

</script>


</head>
<body>
      <p id="geolocation">Watching geolocation...</p>
    <button id="button"> Watch</button>
    <textarea id="result" cols="100" rows="10"></textarea>






</body></html>

20,382

Author by

mr.x

Updated on August 12, 2020

Comments

mr.x over 3 years

I tried this code :

<!DOCTYPE html>
<html>
  <head>
    <title>Location Location Location</title>

    <script type="text/javascript" charset="utf-8">

    var watchID = null;

    // PhoneGap is ready
    //
    function f() {
        // Update every 1 ms seconds
        var options = {enableHighAccuracy: true,timeout: 5000,maximumAge: 0,desiredAccuracy: 0, frequency: 1 };
        watchID = navigator.geolocation.watchPosition(onSuccess, onError, options);
    }

    // onSuccess Geolocation
    //
    function onSuccess(position) {
        var xmlhttp;
        if (window.XMLHttpRequest){// code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp=new XMLHttpRequest();
        }else{// code for IE6, IE5
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
        }       
        var str = 'Latitude: '  + position.coords.latitude      + '<br>' +
                  'Longitude: ' + position.coords.longitude     + '<br>' +
                  'Timestamp: ' + position.timestamp     + '<br>' ;
        var url = "load.php";
        var params = "data="+str;
        xmlhttp.open("GET", url+"?"+params, true);
        document.body.innerHTML += str;
        document.writeln("line 33");
        xmlhttp.send();
        //document.writeln("send");
        //document.writeln(str);
    }

    // clear the watch that was started earlier
    // 
    function clearWatch() {
        if (watchID != null) {
            navigator.geolocation.clearWatch(watchID);
            watchID = null;
        }
    }

    // onError Callback receives a PositionError object
    //
    function onError(error) {
      alert('code: '    + error.code    + '\n' +
            'message: ' + error.message + '\n');
    }

    </script>
  </head>
  <body>
    <p id="geolocation">Watching geolocation...</p>
    <button onclick="f();"> Watch</button>     
  </body>
</html>

you can see that i add

var options = {......, frequency: 1 };
watchID = navigator.geolocation.watchPosition(onSuccess, onError, options);

But I am getting new result if and only if I enter to tab and exit and enter agin.

What can I do?

mr.x almost 10 years

tanx but I want to measure changes between two successive measurements even there is no movem
Luizgrs almost 10 years

The W3C specification clearly says that watchPosition should only callback if the poisition changes. I suggest you to rethink your approach.