Cacher is the code snippet organizer for pro developers

function getAjaxInfo( args ) {
  $.post(
    ajaxurl.url,
    args,
    function( data, textStatus, xhr ) {
      var result = $.parseJSON( data );
  
      if ( result.length !== 0 ) {
        // Success
  
        $('.wrapper').html(result);
  
      } else {
        // Fail
      }
    }
  );
}

$('input[name=something]').change(function() {
  var ajaxArgs = {
    action              : 'pre_ajax_function',
    postDataItem        : $(this).val(),
  }
  getAjaxInfo( ajaxArgs );
});