Callbacks
Callbacks serve to actively respond to user input in a form. Actions can be added to buttons, so that by means of callbacks some dynamics are provided within actions, text-fields and categories and several other types of forms.
A callback of a text box to count the number of characters entered looks eg like this:
var text = helper.getFormValue("SMS versenden", "Text");
println("Text: "+text+" l: "+text.length());
var rest = 160;
if(text!=null){
rest = 160-text.length();
}
println(rest);
helper.setFormValue("SMS versenden", "Restzeichen", ""+rest);
println("Text: "+text+" l: "+text.length());
var rest = 160;
if(text!=null){
rest = 160-text.length();
}
println(rest);
helper.setFormValue("SMS versenden", "Restzeichen", ""+rest);