My first ExtendScript... and it doesn't work - adobe

Question

I am developing a script for Adobe Bridge CS6. For the moment, all I want to do is to access the size (width and height) of a thumbnail that the user has selected and show it, either on a popup or on the console. Here is my script:
function TestBridge() {
this.requiredContext = "\tAdobe Bridge must be running.\n\tExecute against Bridge as the Target.\n";
}
TestBridge.prototype.run = function() {
if(!this.canRun())
{
return false;
}
var selectedThumbnails = app.document.getSelection();
if (selectedThumbnails.length > 0) {
$.writeln("MEEEEEPT");
var thumb = selectedThumbnails[0];
var x = thumb.core.preview.preview.width;
var y = thumb.core.preview.preview.height;
//alert('MEEEEEPT: x = ' + x + ', y = ' + y);
$.writeln("MEEEEEPT: x = " + x + ", y = " + y);
return true;
}
$.writeln("MOOO");
return false;
}
TestBridge.prototype.canRun = function()
{
// Must be running in Bridge & have a selection
if( (BridgeTalk.appName == "bridge") && (app.document.selectionLength == 1)) {
return true;
}
// Fail if these preconditions are not met.
// Bridge must be running,
// There must be a selection.
$.writeln("ERROR:: Cannot run.");
$.writeln(this.requiredContext);
return false;
}
The only problem is that... well, it doesnt work. I open it on ExtendScript Toolkit, set the target to Bridge CS6, hit "Run"... and all that happens is that the console says "Result: canRun()".
Looking at other code samples from Adobe, I see that the structure of their scripts is pretty much the same as mine, so I don't really know what I'm doing wrong.
Edit: what I needed was to add in the end a line to call the function, like so:
new.TestBridge.run();
Silly, silly mistake.