Check if textboxes have the same content - textbox

Question

I want to check if the textboxes created like this:
(function(arr) {
for (var i = 0; i < arr.length; i++) {
app.add(app.createLabel(arr[i] + " mail"));
app.add(app.createTextBox().setName(arr[i]));
}
})(["first", "second", "third"]);
have the same contents? I was looking for something like getElementByTagname or or getTextboxes, but there are no such functions.
So how to iterate thvrough them and show a label if they are all equal?

Answer 1

To access any widget values you need to add them as a callback element (or a parent panel) to the server handler that will process them. The values of each widget are populated on a parameter passed to the handler function and can be referenced by the widget name (that you already set).
You don't need to setId as suggested on another answer. Unless you want to do something with the widget itself (and not its value). e.g. change its text or hide it, etc.
var textBoxes = ["first", "second", "third"];
function example() {
var app = UiApp.createApplication().setTitle('Test');
var panel = app.createVerticalPanel();
textBoxes.forEach(function(name){
panel.add(app.createLabel(name + " mail"));
panel.add(app.createTextBox().setName(name));
});
panel.add(app.createLabel('Example Label').setId('label').setVisible(false));
var handler = app.createServerHandler('btnHandler').addCallbackElement(panel);
panel.add(app.createButton('Click').addClickHandler(handler));
SpreadsheetApp.getActive().show(app.add(panel));
}
function btnHandler(e) {
var app = UiApp.getActiveApplication(),
allEqual = true;
for( var i = 1; i < textBoxes.length; ++i )
if( e.parameter[textBoxes[i-1]] !== e.parameter[textBoxes[i]] ) {
allEqual = false; break;
}
app.getElementById('label').setVisible(allEqual);
return app;
}
Notice that ServerHandlers do not run instantly, so it may take a few seconds for the label to show or hide after you click the button.

Answer 2

When you create the textboxes, assign each one an id using setId(id).
When you want to obtain their reference later, you can then use getElementById(id).
Here is an example:
function doGet() {
var app = UiApp.createApplication();
app.add(app.createTextBox().setId("tb1").setText("the original text"));
app.add(app.createButton().setText("Change textbox").addClickHandler(app.createServerHandler("myHandler")));
return app;
}
function myHandler() {
var app = UiApp.getActiveApplication();
app.getElementById("tb1").setText("new text: in handler");
return app;
}