JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text">

JavaScript

$(document).on('keydown', function(e)
{
   var shifted = e.shiftKey;
   var downTime = parseInt( $(this).attr( "data-startTimer") );
   console.log( shifted );
   if ( shifted && isNaN( downTime ) )
   {
     console.log( downTime );
     $(this).attr( "data-startTimer", new Date().getTime() );
   }
});

$(document).on('keyup', function(e)
{
  var downTime = parseInt( $(this).attr( "data-startTimer") );
  if ( !isNaN( downTime ) )
  {
     console.log( ( new Date().getTime() - downTime ) );
     if (  ( new Date().getTime() - downTime ) >= 5000 )
     {
	    console.log( "yesss" );
        alert( "you held shift key for 5 seconds or longer" );
     }
  }
  $(this).attr( "data-startTimer", "null" );
});