Just simple JS function

func.js

function isGreater(a, b, cb) {
  var greater = false;
  
  if (a > b) {
    greater = true;
  }
  
  cb(greater);
}

var greater;

isGreater(1, 2, function (result) {
  if (result) {
    greater = true;
  } else {
    greater = false;
  }
});