Validate age/date 18 years or not

ValidateDOB.js

// Validate DOB 18 years or not
jQuery.validator.addMethod( "stValidDOB", function(value, element) {
  var dob = value.split("-");

  var year = dob[0];
  var month = dob[1];
  var day = dob[2];
  var age = 18;

  var mydate = new Date();
  mydate.setFullYear(year, month-1, day);

  var currdate = new Date();
  var setDate = new Date();

  setDate.setFullYear(mydate.getFullYear() + age, month-1, day);

  if ((currdate - setDate) > 0){
    return true;
  }else{
    return false;
  }
}, "Sorry, you must be 18 years of age to apply" );