Validation of customized text fields

[ferHN]

Hello, I am a novice in JS , I want to validate a text field , say that this question : Enter the capital of Spain : < text field > , then the answer is there Madrid, then I want an alert "right answer" if you enter Madrid and alert " Wrong answer " if you write another word appears. Greetings.

[try67]

Do you want this message to appear as soon as the user exits the field, or when you press a button to grade the test?

[ferHN]

When the user leaves the field.

[try67]

The use this as the custom validation script of that field:

if (event.value) {
    if (event.value=="Madrid") app.alert("Right answer.",3);
    else app.alert("Wrong answer.");
}

[ferHN]

Thanks for your help.