How does it work, that typing in an open text box OR making a dropdown decision, leads to an automatic display in another box?

Question

Dear Sir or Madam,

how does it work, that typing in an open text box OR making a dropdown decision, leads to an automatic display in another box?
More concretely:
It is planned that subjects will allocate a sum of money to themselves and another subject. If the subjects now indicate in an open text field or dropdown-field how much they are taking, we would like another field to display what another subject is receiving because of this decision. The subjects shell see, how it's decision leads to the payoff of an other subject.

Thank you for your help!
I am pleased about your feedback.

Greetings, Sarah Löffler

Answer 1

For any change within a page, you'll need some JavaScript.

For your case, you put a handler on the onkeyup (text input) or onchange (dropdown) event of the respective input, and then trigger whatever action you would like to.

When you have read the basics about JavaScript in a questionnaire (see above) and want to give a few more details, don't hestitate to ask a "related question" in the online support.