How to pass JavaScript values to JSF EL and backing bean?

Question

I am doing JSF geolocation service where I need to pass latitude and longitude to bean for processing. HTML5 allows getting location with JavaScript, for example like is done in http://code.google.com/p/geo-location-javascript/. Putting following code to JSF page shows alert with GPS coordinates

<script>
    if (geo_position_js.init()) {
        geo_position_js.getCurrentPosition(success_callback,error_callback,{enableHighAccuracy:true,options:5000});
    } else {
        alert("Functionality not available");
    }
    function success_callback(p) {
        alert('lat='+p.coords.latitude.toFixed(2)+';lon='+p.coords.longitude.toFixed(2));
    }

    function error_callback(p) {
        alert('error='+p.message);
    }
</script>

How to use p.coords.latitude.toFixed(2) value to pass it for example to h:inputtext component?

Answer 1

You need to realize that JSF runs at webserver and produces a bunch of HTML/CSS/JS code which get sent from webserver to webbrowser and that the webbrowser only runs HTML/CSS/JS. Rightclick the page in webbrowser and choose View Source. In place of the <h:inputText> you'll see something like

<input type="text" id="formid:inputid" />

In JS, you can easily grab HTML elements from the HTML DOM using document functions and alter it.

var input = document.getElementById('formid:inputid');
input.value = 'new value';

See also:

• Communication between Java/JSP/JSF and JavaScript