Validation to confirm that the inputted date is greater than or equal to today's date

dateValidation.js

// This validation is used inside an ASP.net WebForms application.

function dateValidation(source, args) {
  var today = new Date();
  var parsedInputDate = new Date(args.Value.replace(/(\d{2})\/(\d{2})\/(\d{4})/, '$3-$2-$1')); // This assumes the splitting of date parts on the input is a "/"
  
  function stripTime(inputDate) {
    var strippedInputDate = new Date(inputDate.getFullYear(), inputDate.getMonth() + 1, inputDate.getDate()); // Require to add one to the month as in JavaScript January is month 0
    return strippedInputDate;
  }
  
  var strippedTodaysDate = stripTime(today);
  var strippedParsedInputDate = stripTime(parsedInputDate);
  
  if (strippedParsedInputDate >= strippedTodaysDate) {
    // Date Validation Passed
  } else {
    // Date Validation Failed
    document.getElementById(source.previousElementSibling.id).value = ''; // This will clear the textbox, and get the appropriate TextBox ID depending on what is calling the validation
  }
}

i want to perform on on key up event , not working