Running a script to check box based on other fields. How do I set the box default to unchecked when fields are blank?

[mynameisjberg]

I have a script that checks a box when a person's age is within 10 years of another person. The script works fine, but the box is checked by default until the information is filled in. This confuses some people, so I'm trying to set the default to unchecked. Here is the script:

var fieldT = this.getField("Checkbox 1");

var x = this.getField("Age").valueAsString; 

age = event.value; 

if (Math.abs(Number(x)-Number(age))<=10){

fieldT.checkThisBox(0,true);

}

else

{

fieldT.checkThisBox(0,false);

}

I appreciate any and all assistance. Thanks!

[try67]

Do you mean when the Age field is empty?

[mynameisjberg]

Yes, sorry for not clarifying.

[try67]

Change this line:

if (Math.abs(Number(x)-Number(age))<=10){

To:

if (x!="" && Math.abs(Number(x)-Number(age))<=10){