How to transmit the data?

In this script I create a window with an Edittext field and two buttons. The user can write something in Edittext field. How to read these data? I want to use it like a pattern in regular expressions.

I made an Edittext field a variable. How to transmit the data from it?

function SnpCreateDialog()
{
this.windowRef = null;
}

SnpCreateDialog.prototype.run = function()
{
// Create a window of type palette.
var win = new Window("palette", "Поиск",[100,100,400,250]);  // bounds = [left, top, right, bottom]
this.windowRef = win;

// Add a frame for the contents.
win.pnl = win.add("panel", [25,15,275,135], "Введите данные для поиска");

// Add the components, two buttons
    var txt = win.pnl.add("edittext", [15,25,230,45],"");
    //win.pnl.txt = win.pnl.add("edittext", [15,25,230,45],"");
win.pnl.okBtn = win.pnl.add("button", [15,75,105,95], "OK");
win.pnl.cancelBtn = win.pnl.add("button", [140, 75, 230, 95], "Cancel");

// Register event listeners that define the button behavior

var re = new RegExp(pattern);
   
    win.pnl.okBtn.onClick = function() {
  $.writeln("OK pressed");
  alert(re);
        //win.close();
};
win.pnl.cancelBtn.onClick = function() {
  $.writeln("Cancel pressed");
  win.close();
};

// Display the window
win.show();
 
return true;
   
//var re = new RegExp (txt);
//alert(re);
}

if(typeof(SnpCreateDialog_unitTest) == "undefined") {
    new SnpCreateDialog().run();
}