Is it possible to have an static variable in a handler? - google-apps-script

Question

I want to make an script that keeps track of the times a button is pressed. It is well known that javascript lacks of support for static vars but this can normally be workaround defining the variable outside of the target function.
Nevertheless this does not work for me on a simple google scripting web application. The code is the following one and it is a simple extension of the template web aplication.
Anyone knows how can this be achieved?
This is the code of the google application:
// Script-as-app template.
function doGet() {
var app = UiApp.createApplication();
var button = app.createButton('Click Me');
app.add(button);
var label = app.createLabel('The button was clicked.')
.setId('statusLabel')
.setVisible(false);
app.add(label);
myClickHandler.counter = 0;
var handler = app.createServerHandler('myClickHandler');
handler.addCallbackElement(label);
button.addClickHandler(handler);
return app;
}
function myClickHandler(e) {
var app = UiApp.getActiveApplication();
var label = app.getElementById('statusLabel');
label.setVisible(true);
label.setText('Clicked ' + myClickHandler.counter + ' times.')
myClickHandler.counter++;
//app.close();
return app;
}

Answer 1

There are a few possible ways to achieve that, here is one of them using a hidden widget to hold values.
function doGet(){
var app = UiApp.createApplication();
var button = app.createButton('Click Me');
app.add(button);
var counterValue = 0;
var label = app.createLabel('The button was clicked.')
.setId('statusLabel')
.setVisible(false);
var counter = app.createHidden('counter').setId('counter').setValue(counterValue)
app.add(label).add(counter);
var handler = app.createServerHandler('myClickHandler');
handler.addCallbackElement(counter);
button.addClickHandler(handler);
return app;
}
function myClickHandler(e) {
var app = UiApp.getActiveApplication();
var label = app.getElementById('statusLabel');
label.setVisible(true);
var counterValue = Number(e.parameter.counter)
var counter = app.getElementById('counter')
counterValue++;
counter.setValue(counterValue.toString())
label.setText('Clicked ' + counterValue + ' times.')
return app;
}