How can I create a textfield that checks the input value without the need of a button?

Hi everyone,

I´m trying to create a textfield to check the input (word) and pops up a message in case the answer is right.

The problem is: In ase the answer is wrong and the user mouseclick the textfield again, the message pops up again, before the field is cleared.

I´m using the following script in the Custom Keystroke Format section:

if(event.value == "on"){

app.alert ("Congratulations!", 3,0);

}

else if (event.value == "in"){

app.alert("Incorrect answer. Try again", 0,0);

}

else if (event.value == "at"){

app.alert("Incorrect answer. Try again", 0,0);

}

Thanks a lot in advance for your help!!