XMLHttpRequest to PHP script - what's missing here?

Question

This is my first time using AJAX, and I'm trying to send JS variables to a PHP script. I've got an XMLHttpRequest but it doesn't seem complete - what am I missing?

    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(successFunction, errorFunction);
    }
    else {
        document.write("Geolocation is required for this page.");
    }

    function successFunction(position) {
        var lat = position.coords.latitude;
        var lng = position.coords.longitude;
    //    document.write("<a href='http://api.geonames.org/findNearbyPlaceNameJSON?lat="+lat+"&lng="+lng+"&username=sebastiano'>my town</a>");

        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");
        }

        xmlhttp.open("GET","location.php?lat=position.coords.latitude",true);
        xmlhttp.send();

        // SOMETHING MISSING HERE?

    }

    function errorFunction(position) {
        document.write("Error");
    }

If this is your first time dealing with Ajax, I reccomend you not to do it by your self and use a common simple library such as jquery.com you will be able to make your application much more reacher. — fatnjazzy
– fatnjazzy, Commented Jul 6, 2011 at 13:18
Thanks for your reply, are there any tutorials or search terms I can try to make this easier? — Sebastian
– Sebastian, Commented Jul 6, 2011 at 13:19
net.tutsplus.com/tutorials/javascript-ajax/… is a good overview, otherwise just serach for jquery ajax. — Drazisil
– Drazisil, Commented Jul 6, 2011 at 14:46

JConstantine · Accepted Answer · 2011-07-06 13:19:24Z

3

It appears that you're not passing the contents of your variable to the open command.

xmlhttp.open("GET","location.php?lat=position.coords.latitude",true);

in this example your lat will contain a string with contents "position.coords.latitude"

instead try

xmlhttp.open("GET","location.php?lat="+position.coords.latitude,true);

Or better yet, use the variables you created at the top of the function and pass both long and lat in.

xmlhttp.open("GET","location.php?lat=" + lat + "&long=" + lng,true);

answered Jul 6, 2011 at 13:19

JConstantine

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4 Comments

Sebastian Over a year ago

Thanks, I hadn't noticed that. How can I tell if my external PHP is receiving these values?

JConstantine Over a year ago

Quickest way, not necessarily the best, would be to set up a function in the location.php page that emails you the contents of the two variables.

Sebastian Over a year ago

Is there a way of printing it in the window of the index file?

JConstantine Over a year ago

You can echo the values in your location.php file and then output the response in your index file. You'll need an event handler to listen for xmlhttp request complete which will give you the response data

beardhatcode · Accepted Answer · 2011-07-06 13:22:36Z

2

you are sending it with "position.coords.latitude" as value...

try xmlhttp.open("GET","location.php?lat=" + position.coords.latitude,true);

Also, take a look at jQuery

answered Jul 6, 2011 at 13:22

beardhatcode

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Comments

fitne · Accepted Answer · 2011-07-06 13:58:26Z

1

Try this:

        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");
        }

        xmlhttp.onreadystatechange=function(){
                if (xmlhttp.readyState==4 && xmlhttp.status==200){
                        console.log(xmlhttp.responseText);
                }
        }

        xmlhttp.open("GET","location.php?lat=" + position.coords.latitude,true);
        xmlhttp.send();

answered Jul 6, 2011 at 13:58

fitne

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1 Comment

fitne Over a year ago

here you need to echo the result inside location.php, then this code will log it to console. you can use it as string (i.e. you can alert etc. if you like).

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