Task Script variable as input to DMN

hi ,
im just starting learning,
so i have a javaScript script task that count age based from birth date :

load(‘http://localhost:8080/js/moment.js’);

var inputString = execution.getVariable(“jsonString”);
var jsonParsedB =
moment().diff(inputString, ‘years’);
execution.setVariable(“jsonParsed”,jsonParsed);

my question is, how do i get the resulted age from this as an input to this DMN