how to share the variable to different function on the same class

Question

I want to print what I input in wordpress, but I still not get the variable from different function in the same class The following is my code:

class Test{
    private $infos;
      
    function get_info() {
        if ( isset($_REQUEST['my_info']) ) {
            $this->infos = $_REQUEST['my_info'];
            echo 'your input is:'.$this->infos;
        }
        
        // Always die in functions echoing ajax content or it will display 0 or another word
    //    die();
    }
    
    function salcodes_year() {
        echo 'the data is:'.$this->var;
        return $this->var;        
    }

    function js2php_register(){
        add_action( 'wp_ajax_test_info', array($this, 'get_info') );
        add_action( 'wp_ajax_nopriv_test_info', array($this, 'get_info') );
        add_shortcode( 'current_year', array($this, 'salcodes_year') );
    }
    
}

$test = new Test;
$test->js2php_register();

Version: WordPress 5.8.2 PHP 7.4.27 MySQL 5.7.37 Community Server (GPL)

Help me, please!